Record-Breaking Heat Wave Scorches Western U.S.

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The western United States is experiencing an intense heat wave that is shattering temperature records and raising serious concerns about the growing threat of climate change. Temperatures are soaring 20 to 30 degrees Fahrenheit above normal, with some areas reaching levels typically associated with summer months. This extreme heat is being driven by a remarkably strong high-pressure system, or ridge, over the Southwest, and is exacerbated by the effects of an atmospheric river bringing additional warmth to the region.

Why it matters

The sudden onset of such intense heat poses significant health risks, particularly for vulnerable populations, and also creates ideal conditions for wildfires due to low snowpack and drought conditions across much of the West. This event suggests that what was once considered exceptional is becoming more commonplace, as the frequency and intensity of extreme weather events continue to increase due to climate change.

The details

On Wednesday, North Shore, California, matched its hottest March temperature on record at 108 degrees Fahrenheit. Phoenix, Arizona, reached 105 degrees Fahrenheit, the earliest such recording by more than a month. A location just outside Martinez Lake, Arizona, hit 110 degrees Fahrenheit – the highest March temperature ever recorded in the U.S. This extreme heat is driven by a remarkably strong high-pressure area, or ridge, over the Southwest. The condensation of water vapor from an atmospheric river following record-breaking rainfall in Hawaii is also contributing to the warming trend.

• On Wednesday, North Shore, California, matched its hottest March temperature on record at 108 degrees Fahrenheit.
• Phoenix, Arizona, reached 105 degrees Fahrenheit, the earliest such recording by more than a month.
• A location just outside Martinez Lake, Arizona, hit 110 degrees Fahrenheit – the highest March temperature ever recorded in the U.S.

What they’re saying

What’s next

Researchers will continue to monitor the situation and study the long-term implications of this extreme heat wave on the region's climate and environment.