Chilly changes coming to western US following record-challenging heat
Snow will fall and accumulate over the Rocky Mountain States as much cooler air with showers reach Southern California and the deserts into Friday. High winds will raise the wildfire risk in New Mexico.
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Temperatures have been trending downward over much of the western United States after peaking late last week and over the weekend. However, a much bigger downward step is in progress late this week and will include accumulating snow for some areas and heavy thunderstorms for others, AccuWeather meteorologists warn.
"Last week’s 100-degree reading on April 10 tied as the third-earliest date in the calendar year that Phoenix hit 100 degrees," AccuWeather Senior Meteorologist Chad Merrill said. "The earliest 100-degree reading was on March 26, 1988."
Highs trended downward through the 90s over the weekend at Phoenix. After another day with highs in the 90s on Wednesday, another big drop in temperature is in store, with highs projected to be in the 80s on Thursday but only in the 70s on Friday.
Similarly, where tens of thousands gathered in the heat for the first weekend of Coachella 2025, near Palm Springs, California, temperatures reached 100 degrees on Friday and Saturday with Sunday only slightly cooler. Those heading to the festival this weekend may encounter gusty showers and thunderstorms on Friday before highs more typical for mid-April are in store (mid-80s to near 90) for Saturday and Sunday with sunshine.
Many areas just inland of the Pacific coast in Southern California had one of their warmest stretches for the calendar late last week. "The Burbank and Pasadena, California, areas had their fifth warmest April 9-11 on record, with an average high temperature of 85 degrees," Merrill said. "High temperatures trended into the 70s over the weekend and will further cool this week with highs within a couple of degrees of 60 on Thursday and Friday."
As a big dip in the jet stream develops into Friday, locally drenching and gusty showers and thunderstorms will erupt from portions of Montana and Idaho to California and Nevada.
Because the recent warmth may have warmed up the snow cover on the higher elevations, it may be prone to rapid melting when combined with downpours from thunderstorms through Friday in some locations. This includes the Sierra Nevada, where short-run streams and rivers already swollen from the spring thaw could surge to dangerous and damaging levels.
Any of the thunderstorms that erupt could become briefly severe with damaging wind gusts and hail in a few locations.
Gusty winds will kick up ahead of the temperature drop from the deserts to the southern Plains, where they can cause dust storms and raise the wildfire risk. Later in the week, as the colder air settles in, gusty winds are also in store along the Pacific coast, especially over the mountains, passes and canyons.
A high to very high wildfire will exist over a large part of New Mexico from Thursday to Friday.
The pattern change will begin at midweek over the northern Rockies then progress southward over much of the West on Thursday and Friday.
Meanwhile, Denver set a record-high temperature on Friday with a high of 86. Temperatures surged well into the 70s during Thursday afternoon. By late Thursday night and Friday, it will get cold enough for snow as a storm drops southward over the Rockies. Several inches of snow are forecast to fall over the northern and central Rockies, Tetons and Wasatch Range, and slippery travel over the passes is likely.
From 1 to 3 inches of slushy snow is in store around the Denver metro area with much heavier amounts to the west and south. Several inches are forecast for the Colorado Springs area.
As the pattern evolves this week, low clouds and fog along the Southern California coast from Santa Barbara and Los Angeles to San Diego will become more noticeable, longer lasting and widespread.
"Motorists should be mindful of the reduced visibility that will require extra transit time, in light of recent mornings with relatively clear conditions," Merrill said. "The upcoming showers and thunderstorms forecast for the same area beginning around midweek can also make for extra slick conditions on the roads until oil deposits from recent weeks are washed away."
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