Early Southwest heat is latest in parade of weather extremes

A record-breaking heatwave has hit the southwestern United States, and scientists say it is a clear sign of accelerating climate change.

Key facts:

Temperatures reached 110°F (43°C) in Arizona — the highest March temperature ever recorded in the U.S. 

Many cities including Phoenix, Las Vegas, and Los Angeles also broke long-standing heat records. 

The heat is 20–30°F above normal for this time of year. 

Why this is important:

Scientists say this kind of heat in March would have been “virtually impossible” without human-caused climate change.

Climate change has already increased temperatures by several degrees, making extreme heat more frequent and more intense. 

Impact:

Hiking trails and outdoor areas have been closed due to health risks. 

Around tens of millions of people are affected by the heatwave.

Experts warn infrastructure and emergency systems are struggling to keep up with these extreme conditions. 

Bigger trend:

Extreme weather events (heatwaves, floods, storms) are becoming more frequent worldwide.

Scientists say what used to be rare events are now becoming “normal patterns” in a warming world.