Summary
Across the U.S. Southwest, a dangerous heat wave shattered March temperature records and arrived months ahead of what many communities typically expect. The episode included readings of 112 degrees Fahrenheit (44.4 Celsius) in two Arizona communities, and the same temperature was recorded in two places in Southern California, all clustered within about 50 miles (80.5 kilometers), according to an Associated Press report dated March 20.
Researchers and disaster experts who spoke about the episode said the significance goes beyond any single spike in temperature. They described it as an example of “ultra-extreme” weather conditions showing up in unusual places and months, a pattern that they said increases the number of people facing lethal heat.
“This is what climate change looks like in real time: extremes pushing beyond the bounds we once thought possible,” said University of Victoria climate scientist Andrew Weaver, in comments carried in the AP report. Weaver said events that once were “unprecedented” were becoming recurring features in a warming world, the report said.
A flash analysis by World Weather Attribution — described by the group as not peer-reviewed yet — looked at whether human-caused climate change helped drive the March heat. The group concluded that “events as warm as in March 2026 would have been virtually impossible without human-induced climate change,” according to the AP report.
World Weather Attribution also reported that the warming effect from burning coal, oil and natural gas added between 4.7 degrees and 7.2 degrees Fahrenheit (2.6 to 4 degrees Celsius) to temperatures people experienced during the heat wave, the report said. Report co-author Clair Barnes of Imperial College London, an attribution scientist, said human-caused warming increased the temperatures tied to the heat dome and would push conditions from what would have been uncomfortable into potentially dangerous ranges.
Beyond the Southwest, other scientists told AP that “giant events” are increasingly appearing across climate extremes. Stanford University climate scientist Chris Field said the Southwest heat wave fits that category, describing temperatures as up to 30 degrees Fahrenheit (16.7 degrees Celsius) above normal, and he pointed to other recent examples including a 2020 Siberia heat wave, the 2021 Pacific Northwest heat wave, and extreme events in 2022 and 2023.
The AP report also cited World Weather Attribution’s comparison points and the broader trend lines researchers use to characterize rising extremes. The report said the U.S. area experiencing extreme weather in the past five years has doubled compared with 20 years earlier, based on the National Oceanic and Atmospheric Administration’s Climate Extremes Index. The report added that AP’s analysis of NOAA records found the U.S. breaking 77% more hot weather records than it did in the 1970s and 19% more than in the 2010s, and that inflation-adjusted billion-dollar weather disasters have increased sharply in recent years compared with longer-term baselines, citing NOAA and Climate Central.
For officials who plan for disasters, experts told AP the problem is not only more extremes but also that they are arriving outside the historical expectations built into emergency systems. Craig Fugate, who directed the Federal Emergency Management Agency until 2017, said through email that flood maps, surge models, and heat records increasingly showed up “outside the envelope we built systems around,” and that communities had relied on “about 100 years of past weather” as a guide. Fugate added that the “clearest signal isn’t the science debate,” but “it’s insurers walking away,” according to the report.
As the AP report described it, scientists and meteorologists said the Southwest heat wave is also part of a wider record of worsening weather hazards that include hurricanes, drought, downpours and wildfires. The reporting included examples cited by experts ranging from West African floods in 2022 and 2024 to Iran’s drought and Typhoon Haiyan in the Philippines in 2013, and it referenced research on previous major U.S. storms and wildfire impacts, with climate scientists and communicators warning that heat and dryness can amplify multiple hazards at once.
“This is due to climate change, that we see more extreme events, and more intense ones and have so many records being broken,” Friederike Otto, an Imperial College of London climate scientist who coordinates World Weather Attribution, said in the Associated Press report. The reporting framed the March heat wave as another signal that, as Earth warms, the boundary of what counts as “extreme” keeps shifting.