Temperatures soared dangerously high across south and central Texas on Wednesday amid what forecasters with the National Weather Service called “one of the hottest May heat waves of all time.” Multiple records are expected to fall as the heat lasts well into next week. By 5 p.m., Austin had reached 101 degrees, surpassing its same-day record of 97 set in 2022. Earlier forecasts had indicated the city might reach 105 degrees, breaking the 104 degree record for the hottest day in May. It’s common for Austin or anywhere in Texas to reach the 100s in the summer, but Orlando Bermúdez, a forecaster in the Weather Service’s Austin and San Antonio office, said on Wednesday that an average high there for this time of year is 87 degrees. “This is something we see in mid-June and definitely in July and August,” Mr. Bermudez said. “But this early in May? This is rare.” The heat wave began on Tuesday with many locations in the central and southern parts of the state breaking 100 degrees. On Wednesday, temperatures in those regions ranged from 100 to 111 — levels that are considered dangerous to anyone who can’t escape to an air-conditioned space and pour a cold glass of water. Most other areas of Texas are forecast to see temperatures in the 90s. Matthew Brady, a meteorologist with the Weather Service, said the risk for heat-related illness was high, because “many will not be acclimated to this type of heat so early within the year.” Little relief is expected at night, with overnight lows in many locations likely to dip only into the upper 70s, compared with the lows in the mid-60s that are typical for this time of year. While tying a single heat wave to climate change requires analysis, scientists have no doubt that heat waves around the world are becoming hotter, more frequent and longer lasting. Last year was Earth’s hottest year in recorded history; the 10 warmest years in the history of accurate record-keeping (which spans the past 175 years) have been the past 10. Energy use soared on Tuesday and even more so on Wednesday as Texans blasted air-conditioners. Texas’ electrical grid is under increased stress as new manufacturing plants and data centers for artificial intelligence and cryptocurrencies are opening in the state. By late Wednesday afternoon, the demand for energy reached over 78,000 megawatts, surpassing the previous May record of 77,000 megawatts from last year, according to the Electric Reliability Council of Texas, the organization operating Texas’ grid. Doug Lewin, an energy consultant who writes a newsletter focused on the state’s electricity grid, said the reliance Texans have on their air-conditioners is “very different” at 100 versus 105 degrees. But he said he expected the grid to be prepared to meet the demand. The record-breaking heat was caused by a dome of high pressure that started to move into Texas on Tuesday and was directly over the state on Wednesday. The high pressure in the atmosphere acts like a lid, trapping hot air and pushing it toward the Earth’s surface. “When that air touches the ground, that heats the air just above the surface,” Mr. Bermúdez said. Relief from the scorching weather is not expected until late next week. Areas around Austin and San Antonio are expected to break daily records for the next several days, a run of hot weather that Mr. Brady called “definitely unusual” for this time of year. The hot weather comes after Texas saw normal-to-below-normal temperatures at the start of May as well as thunderstorms that brought damaging winds, heavy rain, large hail and tornadoes. The Weather Service called the recent shift to hot weather “one of the more dramatic temperature swings in recent memory.”

Caught up in the tariff spat between the United States and Canada is a little-known treaty that shapes the lives of millions of Americans and Canadians. The 60-year-old treaty governs the water rushing down the Columbia River and its tributaries, which snake from British Columbia through Montana, Idaho, Washington and Oregon, and provides the single largest source of hydropower in the United States. But parts of the treaty expired around the U.S. presidential election. Negotiators were still weeks away from completing the details of an updated version of the treaty when President Joseph R. Biden Jr.’s term ended. Then a decade of talks crashed into President Trump’s hostility toward Canada. He called Canada the “51st state,” slapped tariffs on Canadian exports and fixated on tapping its water as a “very big faucet.” In a contentious call in February with Canada’s prime minister at the time, Justin Trudeau, Mr. Trump included the treaty among the ways he said Canada had taken advantage of the United States. The implication was clear: The treaty could become a bargaining chip in a broader negotiation to remake the relationship between the two countries. Prime Minister Mark Carney and Mr. Trump turned down the heat during their meeting at the White House last week. But the Trump administration has made even treaties with benefits for both sides feel like a negotiation on the edge of a knife. Mr. Trump’s erratic trade policies have thrown uncertainty into the future of the Pacific Northwest, creating new worries around everything from electricity to flood control. Data centers that power the internet and artificial intelligence run off the Columbia River’s power. Twilight soccer games duke it out at riverfront parks funded by local dams. Irrigation from its reservoirs supplies water to rolling acres of Pink Lady and Gala apple orchards. Coordinated dams hold back floods in Portland, Ore., and elsewhere. Mr. Trump touched a raw nerve among Canadians, who have long worried that the United States sees their resources — water in particular — as its to plunder. “They want our land, they want our resources, they want our water, they want our country,” was a mantra Mr. Carney repeated during his successful run for prime minister. “The Canadians feel such a sense of betrayal,” Jay Inslee, until recently the governor of Washington, said in an interview. The treaty ties together an intricate web of cultural and economic interests. “It is not easy to negotiate that,” Mr. Inslee said, “and it makes it much harder when the guy across the table thinks you are a snake in the grass.” A spokesman for British Columbia said there had not been “any movement at all” since the U.S. State Department paused the negotiations as part of a broad review of the country’s international commitments. While that’s typical after a change in administration, “that sounds like a strange euphemism for what’s going on,” Adrian Dix, the province’s energy minister, told almost 600 people in a virtual town hall in March. Mr. Dix said local residents had pulled him aside at the Save-On-Foods market to ask if Canada should pull out of the treaty altogether. “For the people of the Columbia Basin, this is visceral,” he said. “This is part of their lives and histories and souls.” If the pact were to blow up, the United States expects it would become “more difficult to control and predict” hydropower production, and increase uncertainty for preventing floods in the Pacific Northwest, according to a nonpartisan congressional report. The region’s electricity needs could double in the next two decades, according to new estimates from an interstate power council. The discussions to update the treaty before parts expired in 2024 started during the first Trump administration. Mr. Biden paused them briefly, then resumed. In March 2023, the entire congressional delegation from the Pacific Northwest urged getting a deal done. After the slow start, the United States and Canada announced the rough outlines of agreement last summer that reflected a reality far different from what the treaty writers in the 1960s anticipated. The power generated under the original treaty ended up being much more valuable than originally expected, with Canada’s half totaling roughly $300 million a year. That was far more than it needed, so Canada sold a lot of power back to the United States, much to the chagrin of U.S. utilities. The updated plan cut Canada’s take by roughly half over time. That allows the United States to keep more power just as energy demand is growing for the first time in decades. The river’s cheap, clean hydropower has been a major draw for tech companies looking to build data centers over the past two decades, even more so as artificial intelligence increases their hunger for power. “The country, as a whole, needs to understand how important the Pacific Northwest is in that emerging picture,” said David Kennedy, who studies the history of the region at Stanford.

Wildfires erupted across Britain over the past week amid the driest start to spring in nearly 70 years. Fires burned through forested areas in Scotland, Wales and England, coinciding with declining river levels and warnings of drought. In Scotland, a large forest fire near the village of Fauldhouse, west of Edinburgh, broke out late Saturday morning and was still burning on Sunday. The Scottish Fire and Rescue Service deployed around 50 firefighters, supported by a helicopter dropping water over the woodland area. Mainland Scotland remains under an “extreme” wildfire risk warning through Monday, with officials urging the public to take precautions. Residents in nearby areas were advised by the police to keep windows and doors closed as emergency crews worked to contain the blaze. “Human behavior can significantly lower the chance of a wildfire starting, so it is crucial that people act safely and responsibly in rural environments,” officials said. In southwest Wales, a wildfire broke out on Friday evening on the Welsh Government Woodland Estate near Maerdy. Though it was brought under control, the blaze reignited in several places on Saturday morning before being extinguished on Sunday. Last week in England a major wildfire in Dartmoor, Devon, raged across more than 1,200 acres of land before being put out. Devon and Somerset Fire and Rescue Service said at the peak of the blazes, crews from 13 fire stations were deployed to the area, as well as wildlife support officers and a police helicopter. Britain is in a record-breaking year for wildfires. According to data from the Global Wildfire Information System, which tracks fires larger than about 30 hectares, more land in Britain had burned by the end of April than in any full year over the past decade. The risk has been amplified by unusually dry conditions. England has seen its driest start to spring since 1956. The Met Office, Britain’s weather service, reported that April received only 56 percent of its average rainfall, while March saw just 43 percent. In its April report, the European Union’s Copernicus climate service upgraded Northern Ireland and the Republic of Ireland to drought warning status, following an earlier drought watch. In Ireland, a ban on using water for nonessential outdoor activities, like in gardens, was introduced last Tuesday for six weeks. The restrictions were introduced after prolonged dry weather led to sharp drops in reservoir levels. While no such bans have been put in place in Britain, England’s Environment Agency has warned of a medium risk of drought this summer if there is not consistent rainfall. Scotland is already seeing the signs of strain. The Scottish Environment Protection Agency reported falling water levels in rivers across the country, from Dumfries and Galloway in the southwest to Thurso and Black Isle in the far north. Parts of eastern Scotland have gone nearly three weeks without significant rain. Some rain is expected to reach parts of western Scotland by Monday, but largely dry and sunny weather is forecast for the coming days, offering little relief to firefighters battling the blaze in Fauldhouse, in West Lothian.

A slow-moving storm system is expected to fuel intense downpours of widespread showers and thunderstorms from Alabama to Florida and across the Carolinas, Virginia and West Virginia through Wednesday. The storm is meandering its way over the Lower Mississippi Valley, pulling in a blend of warm, moist air from the Gulf of Mexico and the Atlantic into the Southeastern United States. “These slow-moving systems bring a lot of moisture up,” said Bryan Jackson, a meteorologist at the Weather Prediction Center. “They’re not moving much, so they tend to bring repeating rainfall to some of the same areas.” Repeated rounds of heavy rain from this storm since last week have raised the risk of flash flooding in the region. On Sunday, the heaviest rainfall was focused over northern Florida and southern Georgia.Flooding was also a concern for parts of Alabama, northern Mississippi and the Carolinas, where the ground remains saturated from recent storms. The system is forecast to bring further bouts of rainfall and thunderstorms across the Southeast and into parts of the Mid-Atlantic through Wednesday. The Weather Prediction Center said that rainfall could be especially intense along the Southeast coast and in the mountainous regions. Urban areas along the coast of Virginia were also included in the flood outlook as they are especially prone to flooding during periods of heavy rain. “We’re looking at a focus along the Blue Ridge, so that’s the eastern side of the Appalachians,” said Mr. Jackson. “Also, along the Carolina coast, up from Myrtle Beach and eastern North Carolina is another focused area for some significant rainfall.” Farther south, forecasters were concerned for the Miami metro area, where the Weather Prediction Center issued a Level 3 out of 4 risk for flash flooding through Tuesday. Rainfall rates could exceed two inches per hour, with localized totals of three to seven inches, which may lead to significant flooding. A Level 3 out of 4 “slight risk” for flash flooding was also issued from Virginia to the Florida Peninsula. Scattered storms were expected across parts of the Tennessee and Mississippi Valleys, where a Level 1 out of 4 risk is in place. Those areas have seen heavy rains recently, leaving the ground saturated and more prone to flooding. The Raleigh, N.C., office of the Weather Service said it expected two to four inches of rain across central North Carolina, with the heaviest rainfall likely through Tuesday morning. Flood watches had been issued for central and western North Carolina and for portions of western and southeastern Virginia through Tuesday.

A sluggish line of storms continues to deliver repeated rounds of heavy rainfall across the already saturated ground of the Southeast this week, renewing flash flood risks. In New Orleans, where late last month storms dropped a month’s worth of rain in a day, weary forecasters at the local office of the National Weather Service warned that the area’s “tolerance for another round of heavy rain is fairly low.” Across the region on Wednesday, rainfall totals by late afternoon ranged from between one and three inches in most of Southern Louisiana. Metairie, just outside New Orleans, was an outlier, receiving 4.56 inches, according to the National Weather Service in New Orleans. The Weather Prediction Center placed a broad zone from southeastern Texas to southwestern Alabama under an elevated risk for flash flooding, and a slightly higher risk warning was in effect across southern Louisiana and Mississippi. The day’s highest warning was in place across southeast Louisiana, including New Orleans. “There will still be some showers and thunderstorms throughout the afternoon and into tonight,” Peter Mullinax, a meteorologist with the Weather Prediction Center, said. “But the heaviest action is going on this morning.” A flood watch remained in effect in New Orleans through Thursday, according to the National Weather Service. There were only a few reports of minor flooding on Wednesday afternoon in the city. The repeated downpours are the result of storms breaking out along a nearly stationary front, sitting just north of the Gulf Coast. Warm, moist air from the Gulf of Mexico is building up along this front, and a weather system approaching from the west is injecting additional energy into the atmosphere. As a result, the storms are dropping large amounts of rain in a short amount of time to the same areas. The slow-moving storms have already been affecting the region since early in the week, delivering significant rainfall and flooding across parts of Texas and Louisiana. On Monday and Tuesday, areas in Louisiana received two to four inches of rain, with some locations in the west surpassing eight inches over the 48-hour period. In Texas, some areas have already exceeded their average monthly rainfall for May in just the first week. In Amarillo, 2.46 inches of rain was recorded by Wednesday morning, far surpassing the city’s May average of 2.27 inches. “It’s been quite wet for a good chunk of the start,” Mr. Mullinax said. “Some of this is welcomed, especially as we get closer to summer, but to have it be that kind of levels, of course it’s going to cause some flooding problems, and unfortunately that’s been the case the last couple of days, especially in northern and eastern Texas.” In Brenham, Texas, between Austin and Houston, a search operation recovered the body of Devah Woods, 10, on Tuesday. She had last been seen on Monday as storms moved through the area. “The response from everyone was overwhelming,” Atwood Kenjura, the mayor of Brenham, said during a news conference, expressing gratitude to rescue workers. The Brenham Fire Department reported that the search effort had included drones, swift water rescue teams and canine units. Severe weather was an added threat in the Southeast through Thursday, especially across portions of Texas, Oklahoma, Louisiana, Mississippi and Alabama. The Storm Prediction Center warned of hail and damaging winds as the primary threats, along with a low risk of tornadoes. Southeastern Texas, including cities such as Victoria and Missouri City, were under slightly higher risk of severe weather, especially Wednesday afternoon and evening. The Southeast will continue to face severe weather and high rainfall in the coming days. The Weather Prediction Center warned of flash flood risks for parts of Louisiana, Arkansas, Mississippi, Alabama, Georgia, Florida and, later this week, South Carolina. Southeast Louisiana into southwest Alabama, including New Orleans and Mobile, remain under a slightly higher risk. “We’ve got rainfall in the forecast all the next seven days,” Mr. Mullinax said. “It’s just a tough stretch of unsettled weather in the Southeast for the next week.” There were sporadic power outages in the region. About 16,000 households in Louisiana, 8,000 in Mississippi, and 6,000 in Texas had no power, as of early Wednesday evening, according to PowerOutage.us.

At the start of April a deadly torrent of rains caused flooding across the Midwest, as days of severe storms ravaged much of the central part of the United States. A month later, the Mississippi River in New Orleans was finally cresting this week, as much of the water from those storms is ending its long journey south. The river has been gradually rising for weeks and reached 16.7 feet on Thursday. This is just below the flood stage of 17 feet, and far from a record, but it’s the highest water level in New Orleans since 2020, and comes amid a four-year drought in the Mississippi River Basin. “It looks noticeably different than it was just a year ago,” said Robert Florence, a co-owner of NOLA Historic Tours, who led a tour by the river a week ago. “When the water is higher, it accentuates the sinkholes, cross currents, whirlpools and eddies. It feels more alive and powerful.” The Mississippi watershed is the third largest in the world. The Mississippi River is complex and huge. Its main stem flows 2,350 miles from the headwaters at Lake Itasca in Minnesota to the Gulf of Mexico, touching 10 states and spreading out into many more with its tributaries. The water that comes down the river and arrives in New Orleans is a result of rain and snowmelt that has occurred in states as far away as Pennsylvania, Minnesota, Montana, Colorado and Tennessee. In the case of the water pushing into New Orleans right now, it started out as falling rain four weeks ago, mainly over the upper Mississippi River and Ohio River Valleys. Between April 2 and 6, it turned roads into rivers and flooded communities across Arkansas, Missouri, Illinois, Indiana, Kentucky and Tennessee. Some locations recorded over 15 inches of rainfall. The rain was part of a sprawling cross-country storm system that also generated thunderstorms and tornadoes, although most of the damage came from the relentless rainfall, fueled by moisture from the Gulf. Small rivers in the upper watershed rose quickly, some cresting at historic levels, and have already come back down. The flood cycle is longer on the channeled and leveed Mississippi, which is fed by numerous tributaries. The rain in early April turned into runoff and flowed for days, into the upper portion of the lower Mississippi River Basin and its tributaries, including the Arkansas, White and Red Rivers, and especially the Ohio. It can take weeks for the discharge from the Mississippi tributaries to peak, and for that water to eventually travel down the river. “This is the situation we’re seeing now, where heavy rains fell in Kentucky in early April and it will be roughly four weeks before that peak discharge reaches New Orleans,” said Kory Konsoer, associate director of the Center for River Studies at Louisiana State University. As all of that water traveled south, the river swelled along with it, causing additional flooding in some areas, and overtaking roads and farmland that was recently planted. About 250 miles north of New Orleans, Vicksburg, Miss., saw the river rise to near major flood stage earlier this week, then hold there for several days. The river has been closely watched for weeks. It was well-known that the river would peak in New Orleans this week. The National Weather Service provides forecasts, and the U.S. Army Corps of Engineers monitors these closely as it manages the river’s plumbing system of levees, floodways and reservoirs built to prevent major flood disasters. Occasionally, the Army Corps will open spillways and floodways that are designed to divert floodwaters during extreme weather events. It hasn’t opened any since the storms in April, but it did come close. This week, the agency ran tests on the Bonnet Carre Spillway, 30 miles northwest of New Orleans, to ensure it was ready, if needed, to prevent flooding. The spillway is opened when the river is flowing into the Gulf at a rate of 1.25 million cubic feet per second. But Matt Roe, a spokesman for the Corps in the New Orleans district, said the flow was expected to be just shy of that level. “This whole event, it has been very close,” Mr. Roe said. “In the earlier forecast, we were predicted to go beyond that trigger point, but the conditions appear to be coming out a little lower.” The spillway was built in 1931 to remove pressure on the levees protecting New Orleans by diverting up to 250,000 cubic feet of fresh water per second into Lake Pontchartrain’s brackish waters. Since then, it has been used 15 times, five of them between 2016 and 2020. “It’s not the most water that has moved through in the last decade, but it’s still a lot of water,” Mr. Roe said.

Five former National Weather Service directors have taken the unusual step of signing onto an open letter warning that cuts to the organization by the Trump administration may soon endanger lives. “N.W.S. staff will have an impossible task to continue its current level of services,” they write in the letter, dated Friday. “Our worst nightmare is that weather forecast offices will be so understaffed that there will be needless loss of life.” Hundreds of Weather Service employees, or about 10 percent of the agency’s total staff, have been terminated or accepted buyout offers since President Trump began his second term, according to the letter. The letter notes that the coming weeks are “the busiest time for severe storm predictions like tornadoes and hurricanes,” and it points to a wide range of activities that rely on accurate forecasting: “Airplanes can’t fly without weather observations and forecasts; ships crossing the oceans rely on storm forecasts to avoid the high seas; farmers rely on seasonal forecasts to plant and harvest their crops which feed us.” “Perhaps most importantly,” they write, “N.W.S. issues all of the tornado warnings, hurricane warnings, flood warnings, extreme wildfire conditions and other information during extreme weather events.” The loss of staff is already affecting local forecast offices, said Joe Friday, who led the Weather Service from 1988 to 1997 and who signed the letter. “You have offices that cannot maintain their balloon launch schedules,” he said. “You have offices that cannot maintain 24-hour-a-day operations fully staffed.” The more than 100 Weather Service offices around the country have traditionally launched at least two balloons a day to collect data that helps them produce forecast models. In an interview, Dr. Friday said he was concerned that meteorologists who are stretched increasingly thin will be left to issue severe weather warnings with less lead time. “There’s going to be fewer people keeping their eyes on what’s going on,” he said. In addition to Dr. Friday, the letter was signed by Louis Uccellini, who led the Weather Service from 2013 to 2022; Jack Hayes, who led it from 2007 to 2012; D.L. Johnson, who led it from 2004 to 2007; and John J. Kelly Jr., who led it from 1998 to 2004. The Weather Service declined to comment on the letter on Friday. The agency may soon face another challenge. On Friday, the White House published a budget proposal including a $1.5 billion cut in funding to the Weather Service’s parent agency, the National Oceanic and Atmospheric Administration, which has already faced the loss of hundreds of employees. Editors’ Picks How Pickle Lemonade Took Over the Group Chat Kristen Stewart Thinks the Critics at Cannes Are Being Too Nice Living the Slop Life Advertisement SKIP ADVERTISEMENT The budget proposal does not describe specific reductions in funding to the Weather Service, but the cuts planned for NOAA’s research arm could have a profound effect on meteorologists’ capacity to improve forecasting techniques. “Given the interconnectedness of all of the parts of NOAA, there will be impacts to weather forecasting as well,” the letter says. The proposed cuts at NOAA echo a plan laid out in Project 2025, a policy playbook published by the conservative Heritage Foundation in 2023 that described the agency as “one of the main drivers of the climate change alarm industry.” It called for NOAA to be “broken up” and for the Weather Service to be privatized. Dr. Friday said he worried that a forced decline in the accuracy of Weather Service products could eventually offer a pretext for the agency’s privatization. “If you want to basically wipe out an organization, the personnel policies that are going on right now under DOGE are probably about the best way to do it,” Dr. Friday said. “You destroy the organization from the inside.”

A slow-moving storm brought deadly flooding to Oklahoma on Wednesday, shutting down roadways and sweeping away cars. Parts of Oklahoma and Texas were expected to see more rain on Thursday that could cause more flash flooding, the National Weather Service warned, after several inches of rain fell in both states. One man was killed in Pottawatomie County in Oklahoma, the sheriff’s office said, after it received a report of a vehicle that had been swept off the road. A deputy sheriff tried to rescue the man, according to the sheriff’s office, but “was caught in a powerful current and became trapped in a life-threatening situation.” The deputy was transported to the hospital, and the man died at the scene, the sheriff’s office said. In neighboring Lincoln County, an 86-year-old woman from Prague, Okla., died after her vehicle entered into high water and was swept away, said Sarah Stewart, an Oklahoma Highway Patrol spokeswoman. Another passenger in the car, a 58-year-old woman, survived after the Prague Fire Department rescued her, Ms. Stewart added. Parts of central and southern Oklahoma received up to eight inches of rain on Tuesday and Wednesday, with up to six inches falling in parts of Texas. The National Weather Service said areas in southwestern Oklahoma and across the Red River into Arkansas were expected to receive more than an inch of rain, and some spots just north of the river could get over two inches on Thursday. Rainfall could come down at a rate of one to two inches per hour, which would easily overwhelm the already soaked ground. The heaviest rain was expected on Thursday evening and overnight, according to forecasters. Flooding forced road closures in at least 32 counties in Oklahoma on Wednesday, the state’s department of emergency management said Wednesday evening. “Though the water has receded on some of the roadways, the condition of the infrastructure of the roads due to wash outs will need to be inspected for your safety,” Lincoln County’s emergency management department said. Oklahoma’s Highway Patrol warned drivers to avoid floodwater: “Be careful driving if you have to get out. Reduce your speed. And always remember — don’t drive into standing water.” More thunderstorms could bring large hail and more flash flooding to Oklahoma and North Texas throughout the day and night on Thursday, according to forecasters. Storms were expected to continue into Friday, with the risk of flooding spreading farther south and east, especially across central and northeastern Texas, southeastern Oklahoma, central and southern Arkansas and northwest Louisiana, forecasters said. The Weather Prediction Center warned that the region along Interstate 35 between Austin and San Antonio would be especially vulnerable because its terrain and soil does not absorb water well. The interstate was shut down briefly near Oklahoma City on Wednesday because of flooding, the Oklahoma Highway Patrol said. The storms follow severe weather this week in Pennsylvania, where about 240,000 people were still without power on Thursday morning, according to Poweroutage.us. Those storms claimed four lives. The severe weather in Oklahoma and Texas was expected to clear on Friday, but the respite may be brief. Another storm system will approach from the west next week. “Texas and Oklahoma have to get ready for more rounds of heavy rainfall,” said Peter Mullinax, a meteorologist with the Weather Prediction Center. “They’re going to be expecting more rain as we head into the next week again.”

Britons have basked in a burst of summerlike weather this week as temperatures have surged beyond the seasonal average — and they may soon break records. Forecasters say Thursday may be Britain’s warmest May 1, with highs expected to reach 84.2 degrees Fahrenheit (29 Celsius). The heat has been driven by two key factors: a large area of high pressure that has settled over Britain, causing descending air that warms as it sinks, and continuous sunshine, fueling daytime heating. Aidan McGivern, a meteorologist at the Met Office, the nation’s weather service, explained that this has been a familiar pattern over the last few months. “The sun this time of the year is as strong as it is in August,” he said. “We’re not importing this air from anywhere else — this is homegrown warmth.” London recorded Britain’s highest temperature of the year on Monday, only for that to be beaten on Tuesday. The mercury is expected to rise further on Wednesday and Thursday. Overnight temperatures have been above average too, with parts of Scotland experiencing their warmest April night on record. The peak of the heat is expected on Thursday, just as voters in England head to the polls for local elections. Temperatures in southern England could reach 84.2 Fahrenheit, which would be a record for May 1. The current record was set in 1990 in Lossiemouth, Scotland, which hit 81.3 Fahrenheit (27.4 Celsius). If temperatures rise a bit higher, it could also become the earliest date in the year that Britain has hit 86 Fahrenheit (30 Celsius), based on Met Office data going back to 1860. “The most likely temperature we’re expecting is 29 Celsius,” Mr. McGivern said. “But there’s a possibility — a smaller chance of 10 to 20 percent — of 30 Celsius.” Typical highs for Britain in late April are around 54 Fahrenheit in northern areas and 61 in the south. But despite the stretch of warm days, this may not officially count as a heat wave. To qualify as a heat wave in Britain, temperatures must meet or exceed a specific threshold for at least three consecutive days. This threshold varies by region, from 77 Fahrenheit (25 Celsius) in Scotland, Northern Ireland and parts of northern and western England, to 82.4 Fahrenheit (28 Celsius) in southeast England. While many will enjoy the summerlike weather, it’s also bringing risks. The Scottish Fire and Rescue Service and the Scottish Wildfire Forum have issued warnings of a very high to extreme wildfire risk across parts of Scotland. “There are currently vast areas that are tinder-dry and vulnerable, which provides all the ingredients for fire to take hold and spread,” said Michael Humphreys, an area commander with the Scottish Fire and Rescue Service. Although spring wildfires are not unusual in Britain, 2025 has already been a record-breaking year for them. More than 29,200 hectares, or 72,000 acres, have burned so far this year, according to the Global Wildfire Information System, surpassing the previous record of 28,100 hectares in all of 2019. Looking ahead, temperatures are expected to ease slightly starting on Friday, with highs likely dipping to around 77 Fahrenheit (25 Celsius), though the warm conditions could continue in the southeast of England. There’s also a growing chance of thunderstorms, particularly in the south and southwest, late Thursday and into the night. Over the weekend cooler conditions are likely to filter in from the north, bringing temperatures closer to normal.

At least four people were killed in Pennsylvania on Tuesday and hundreds of thousands of customers were without power after severe weather that had torn across the High Plains and Upper Midwest earlier this week pushed into the Northeast and Canada. David Lepinsky, 59, was killed after being electrocuted by live wires, according to the Pittsburgh Public Safety Department. He was pronounced dead at the scene. Another resident, Raymond Gordon, 67, was returning to his home when he was fatally hit by a tree after it blew over, according to the Ross Township Police Department near Pittsburgh. In Centre County, Pa., a 22-year-old man was also killed after being electrocuted while trying to put out a mulch fire during the severe weather, the State College Police Department said in a statement. In Greene County, Pa., a passenger in a car was killed when a tree fell on top of it, the Pennsylvania State Police said in its statement about weather-related calls. The passenger, Andrew Celaschi, was struck by a falling tree that was blown over by high winds, the authorities said. The storm “was tough on our city,’’ Mayor Ed Gainey of Pittsburgh said at a news conference on Wednesday. The National Weather Service office in Pittsburgh said on Wednesday that it had crews in Wilkinsburg, a borough in Allegheny County, Pa., looking for potential tornado damage from Tuesday’s severe weather. The service reported that “a large swath of destructive wind damage” was seen across the area as storms rolled through on Tuesday evening, with gusts as high as 90 mile per hour. The service added that the storms were “stronger than many of the smaller” tornadoes that the meteorologists “typically see in this region, but for a much, much wider area.” More than 400,000 customers in Pennsylvania were without power as of Wednesday afternoon, according to poweroutage.com, which tracks outages nationwide. Duquesne Light Company said that it was working to restore power to customers without service and that some customers could be without service for about five to seven days. The company was requesting assistance from utility partners. The company said that the heavy winds had knocked down trees, broken utility poles and prompted more than 20,000 separate reports of hazards. Officials in Allegheny County, home to Pittsburgh, encouraged residents to stay home as crews with chain saws worked to remove downed trees and clear debris from roads on Wednesday. About 180 trees were knocked down in Pittsburgh, officials said. “Stay in,” Mayor Gainey urged. “Safety is our number one priority.” The same system also rolled through southern Quebec in Canada on Tuesday evening, where a teenage boy was in critical condition in Montreal after a tree toppled and pinned him, according to CBC.com In Quebec, about 49,000 customers were without power on Wednesday afternoon, according to poweroutage.com The outages came amid severe weather with thunderstorms that whipped up winds and unleashed hail as large as Ping Pong balls. As of Wednesday, a total of 14 tornadoes had been confirmed in a handful of states, with most of those occurring in Wisconsin on Monday, and others reported in Kansas, Minnesota, Missouri, Oklahoma and Utah. “In terms of the overall coverage of tornadoes, it was certainly not as many as it could have been,” said Nathan Wendt, a meteorologist with the Storm Prediction Center at the Weather Service. By Wednesday afternoon, the storm activity had pushed offshore. “It should be quiet in the Northeast today,” Mr. Wendt said.