Southwest braces for next heat wave with highs reaching 110 degrees in Phoenix, Palm Springs
A building heat wave will send temperatures soaring across the interior Southwest, with some cities topping 100 to 110 F for the first time this year in the coming days.
A strong ridge of high pressure is driving a major warmup. By Sunday, from Reno, Nevada, to Boise, Idaho, temperatures will be pushing record-challenging levels.
The second heat wave of the year will build across the interior Southwest through Mother's Day weekend, bringing the region’s highest temperatures so far this year. While not as extreme as March’s event, the heat will still be significant.
Highs across much of the interior Southwest will climb to levels not reached since last August.
“Temperatures will rise by 20 to 30 degrees Fahrenheit in just a few days, which may catch people off guard,” AccuWeather Senior Meteorologist Tyler Roys said. “Las Vegas and Fresno, California, could experience their first 100-degree day of the year, with some daily records challenged.”
Temperatures are forecast to reach 110 degrees in Palm Springs, California, and Phoenix—weeks ahead of the typical first occurrence in early to mid-June.
“This is somewhat unusual this early in the season, but it is not nearly as extreme as the March heat wave, which produced departures of 20 to 40 degrees above average,” Roys said. Temperatures climbed well above 100 in Phoenix and Palm Springs and into the upper 90s in Las Vegas during that event.
Temperature departures from the 30-year average will be on the order of 15 to 25 degrees with the current heat wave.
“The surging heat will accelerate mountain snowmelt,” Roys said. “Runoff may cause cold, fast-moving water levels in streams and rivers to rise quickly. Cold water shock is a real risk for anyone trying to cool off.”
“The heat could impact outdoor graduations, festivals, barbecues and Mother’s Day weekend events across the Southwest,” Roys added. “Early-season heat can be especially dangerous because people have not yet acclimated, increasing the risk of heat-related illness.”
Staying hydrated and taking breaks in the shade is critical. AccuWeather RealFeel® Temperatures in direct sunlight can be significantly higher than in the shade, and stepping under tree cover can reduce the body’s heat load by 10 to 20 degrees or more.
A person walks on sand dunes Sunday, Aug. 3, 2025, in Death Valley National Park, Calif. (AP Photo/John Locher)
Hikers are advised to pack extra water, choose shorter routes and limit activity from late morning through midafternoon.
The surging heat and ongoing drought will increase the wildfire risk despite the spring green-up. People spending time outdoors should use extra caution with open flames and spark-producing equipment.
In contrast, temperatures along the California coast will remain moderate, as a marine layer and sea breeze keep the heat in check. This includes San Diego, beach areas near Los Angeles and San Francisco.
In the Northwest, highs along the Interstate 5 corridor will range from the upper 60s to near 80, while areas east of the Cascades in Washington and Oregon will have highs from the 70s into the mid-80s through this week.
“Temperatures at this level will be 10 to 15 degrees above the historical average along the Interstate 5 corridor and 15 to 20 degrees above average across the interior Northwest,” AccuWeather Meteorologist Melissa Constanzer said. “This will bring June-like heat to a region where air conditioning is not widely available.”
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