Extreme Heat Shatters March Records Across Southwest

Scientists say the unprecedented temperatures are a clear sign of climate change's impact.

Mar. 21, 2026 at 2:11pm

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A dangerous heat wave has shattered March temperature records across the U.S. Southwest, with some areas reaching up to 112°F (44.4°C). Experts say this extreme weather event, occurring months ahead of the typical hot season, is a clear sign that climate change is driving more dangerous and unpredictable weather patterns.

Why it matters

The Southwest is accustomed to dealing with deadly heat, but not this early in the year. These record-breaking temperatures, which would have been "virtually impossible" without human-caused climate change, put more people at risk and highlight how global warming is altering the boundaries of what was once considered "normal" weather.

The details

On Friday, two Arizona communities and two locations in Southern California all hit 112°F (44.4°C), shattering the previous highest March temperature recorded in the U.S. This heat wave is part of a broader trend of more extreme weather events, with the area of the U.S. affected by such events doubling in the past five years compared to 20 years ago.

  • On Friday, March 21, 2026, temperatures reached 112°F (44.4°C) in several Southwest communities.
  • Climate scientists say this heat wave would have been "virtually impossible" without human-caused climate change.

The players

Andrew Weaver

A climate scientist at the University of Victoria who says the extreme heat is an example of "what climate change looks like in real time."

Clair Barnes

An attribution scientist at Imperial College of London who co-authored a report finding that human-caused warming added 4.7°F to 7.2°F (2.6°C to 4°C) to the temperatures in this heat wave.

Chris Field

A climate scientist at Stanford University who categorized this heat wave as one of several "giant events" in the last six years, including heat waves in Siberia, the Pacific Northwest, and other regions.

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What they’re saying

“This is what climate change looks like in real time: extremes pushing beyond the bounds we once thought possible.”

— Andrew Weaver, Climate Scientist, University of Victoria

“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.”

— Clair Barnes, Attribution Scientist, Imperial College of London

What’s next

Climate scientists say this heat wave is a clear sign that extreme weather events are becoming more frequent and intense due to climate change, underscoring the need for communities to prepare for and adapt to these new climate realities.

The takeaway

The record-breaking heat in the Southwest is the latest example of how climate change is driving more dangerous weather extremes that are occurring outside of typical seasonal patterns, putting more people at risk and highlighting the urgent need to address the root causes of global warming.