Record-Breaking March Heat Wave Shows Climate Change Impact in Real Time

A dangerous heat wave that shattered March temperature records across the Southwest represents the latest extreme weather event linked to Earth's warming climate. Scientists say temperatures reaching 110 degrees in Arizona would have been virtually impossible without human-caused climate change.

WASHINGTON — The scorching heat wave that demolished March temperature records throughout the Southwest United States represents far more than an isolated weather anomaly. Scientists say it’s the most recent example of increasingly severe weather patterns occurring as global temperatures continue rising.

Weather experts warn that unprecedented and lethal climate extremes are now appearing at unusual times and in unexpected locations, placing more communities at risk. While the Southwest regularly experiences dangerous heat, this wave arrived months earlier than typical, including a 110-degree reading in Arizona’s desert on Thursday that broke the nation’s highest March temperature on record.

Preliminary temperature measurements from Arizona and southern California reached 109 degrees Fahrenheit on Thursday, potentially marking the hottest March day ever documented in the United States.

“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. “What used to be unprecedented events are now recurring features of a warming world.”

According to a Friday report from World Weather Attribution, an international team of researchers studying extreme weather causes, March’s heat wave would have been nearly impossible without human-driven climate change.

Over a dozen scientists, meteorologists and disaster specialists contacted by The Associated Press classified the March heat wave alongside ultra-extreme events including the 2021 Pacific Northwest heat wave, Pakistan’s 2022 flooding, and devastating hurricanes Helene, Harvey and Sandy.

Data from the National Oceanic and Atmospheric Administration’s Climate Extremes Index shows the portion of the United States experiencing extreme weather over the past five years has doubled compared to two decades ago, encompassing various severe conditions from heat waves to droughts and intense rainfall.

The nation now breaks 77% more hot weather records compared to the 1970s and 19% more than the 2010s, based on an Associated Press analysis of NOAA data. Billion-dollar weather disasters in recent years occur twice as frequently and cost twice as much as a decade ago, and nearly four times more than 30 years ago, according to NOAA and Climate Central records.

“It’s really hard to even keep up with how extreme our extremes are becoming,” said Climate Central Chief Meteorologist Bernadette Woods Placky. “It’s changing our risk, it’s change our relationship with weather, it’s putting more people in risky situations and at times we’re not used to. So yes, we are pushing extremes to new levels across all different types of weather.”

Government disaster management officials describe the escalating extremes as a major challenge.

Craig Fugate, who led the Federal Emergency Management Agency through 2017, observed increasing extreme events during his tenure.

“We were operating outside the historical playbook more and more. Flood maps, surge models, heat records — events kept showing up outside the envelope we built systems around. That’s just what we saw,” Fugate said via email.

He continued: “We built communities on about 100 years of past weather and assumed that was a good guide going forward. That assumption is starting to break. And the clearest signal isn’t the science debate. It’s insurers walking away.”

Climate researchers at World Weather Attribution conducted a rapid analysis examining climate change’s role in the Southwest heat wave. Comparing this week’s projected temperatures with March observations since 1900 and computer climate models, they determined that “events as warm as in March 2026 would have been virtually impossible without human-induced climate change.”

The warming caused by burning fossil fuels added between 4.7 and 7.2 degrees Fahrenheit to current temperatures, the analysis found.

“What we can very confidently say is that human-caused warming has increased the temperatures that we’re seeing as a result of this heat dome, and it’s going to be pushing those temperatures from what would have been very uncomfortable into potentially dangerous,” said report co-author Clair Barnes, an Imperial College of London attribution scientist.

Stanford University climate scientist Chris Field categorizes the Southwest heat wave as a “giant event,” with temperatures climbing up to 30 degrees above normal levels.

Field identified five similar events from the past six years: Siberia’s 2020 heat wave, the 2021 Pacific Northwest heat wave that made British Columbia hotter than Death Valley, extreme summer temperatures across North America, China and Europe in 2022, western Mediterranean heat in 2023, and a 2023 South Asian heat wave with dangerous humidity levels.

This list excludes East Antarctica’s 2022 heat wave, when temperatures soared 81 degrees above normal — the largest temperature anomaly ever recorded, according to weather historian Chris Burt, author of “Extreme Weather.”

Scientists told the Associated Press that climate-influenced severe weather extends beyond extreme heat to include destructive hurricanes, prolonged droughts and intense storms.

Catastrophic flooding struck West Africa in both 2022 and 2024. Iran continues experiencing a six-year drought. The deadly Typhoon Haiyan that devastated the Philippines in 2013 stunned global observers.

Superstorm Sandy flooded New York City and surrounding areas in 2012, generating tropical storm-force winds across nearly one-fifth of the continental United States. The storm created 12-foot waves spanning 1.4 million square miles with energy matching five atomic bombs, said Yale Climate Connections meteorologist Jeff Masters.

Recent extremes should also include wildfires intensified by heat and drought, such as 2025’s Palisades and Eaton fires, which became the nation’s costliest weather disaster last year, noted Climate Central meteorologist and economist Adam Smith.

“This is due to climate change, that we see more extreme events, and more intense ones and have so many records being broken,” said Friederike Otto, an Imperial College of London climate scientist who coordinates World Weather Attribution.