An early-season heat wave baking the West this week obliterated numerous all-time records in California and Arizona on Wednesday and Thursday.
The summerlike conditions are expected to persist and expand east in the coming days.
Across Southern California and the Desert Southwest, around 38 million people are under heat alerts. High temperatures in the upper 90s and triple digits have been common throughout the region, thanks to a sprawling heat dome that remains parked over the West.
On Thursday, Palm Springs, California, hit 107 degrees Fahrenheit, setting a new all-time record for the month of March. The previous record, of 105, was set on Wednesday.
The city of Indio in the Coachella Valley also set a record high for March on Thursday, when temperatures climbed to 108 degrees.
A number of daily records were broken across California, as well, including a 101-degree reading in Riverside on Thursday. Records set the prior day included highs of 95 degrees in Anaheim, 88 degrees in Sacramento and 85 degrees in both San Francisco and San Diego, according to the NWS.
In Arizona’s Yuma County, the community of Martinez Lake hit a jaw-dropping 110 degrees on Thursday, setting a new record for the highest March temperature in U.S. recorded history, according to the National Weather Service.
Phoenix, meanwhile, recorded its earliest triple-digit day on Wednesday, with a high of 102 degrees. Temperatures reached 104 degrees there on Thursday.
“This is not only the first 100° day of 2026, but it is also the earliest occurrence of 100° in Phoenix (which last occurred on March 26, 1988),” the local office of the National Weather Service wrote Wednesday on X.
Phoenix is forecast to hit 106 degrees on Friday and Saturday. An extreme heat warning is in effect for the region through Sunday.
Las Vegas has similarly sizzled. On Thursday, the city set a new March record of 95 degrees, according to the local office of the National Weather Service. Temperatures there could reach 100 degrees on Friday.
Even parts of Oregon, Idaho and Wyoming are experiencing unseasonably warm conditions. The National Weather Service office in Boise said Wednesday afternoon that the city measured a high of 80 degrees.
“This is the earliest date for 80 degrees in records dating back to 1875, and only the second time Boise has ever reached 80 in winter, the other time being March 19, 1997,” the NWS office said on X.
Heat will continue to build heading into the weekend and is expected to move east into the Rockies and the central and southern Plains.
“By Saturday, expect maximum temperatures in the middle to upper 90s across Texas and low to middle 90s as far north as Nebraska and South Dakota,” the NWS said Thursday.
Colorado could set new temperature records, as well, with Friday forecasts showing highs of 84 degrees in Denver, 86 degrees in Fort Collins and 83 degrees in Boulder. On Saturday, the projected highs tick up even further. The National Weather Service warned that extreme heat, combined with gusty winds and low humidity, are increasing the risks of wildfires in the state.
This week’s heat dome is caused by a stubborn ridge of high pressure that has trapped hot air over the West like a lid on a pot.
While it can be challenging to tease out the exact influence of climate change on specific weather events, global warming is known to make heat waves more frequent, more intense and longer-lasting.
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