Environment

October heat wave sets dozens of records in California and Arizona

San Jose, California, and Phoenix recorded record highs Wednesday.

People cool off near the water on Alameda Beach in Alameda, Calif., on Wednesday.Jessica Christian / San Francisco Chronicle via Getty Images

More than 50 heat records were set Wednesday as an extraordinary October heat wave continues to bake much of the Western U.S.

A record high temperature of 108 degrees Fahrenheit was recorded in Phoenix, breaking the previous record of 107 degrees set in 1980, according to the National Weather Service. Temperatures in Yuma, Arizona, reached 112 degrees Wednesday, tying the previous record, also set in 1980.

California, too, notched several daily heat records, according to the National Weather Service. A high of 106 degrees was recorded in San Jose, smashing the previous record of 96 degrees in both 1980 and 2012. Napa recorded a high of 103 degrees, topping its previous record of 102 in 1980.

Around 29 million people were under heat alerts Thursday, with excessive heat warnings in effect for much of California, Arizona and Nevada.

Dozens more records are expected to fall from California to Colorado as extreme temperatures persist through the weekend.

Severe heat is expected to continue worsening as a result of climate change, with a wealth of studies showing that as the planet warms, heat waves are becoming more likely, more intense and longer-lasting.

More dangerously hot temperatures in California are expected in the coming days, including highs up to 112 degrees in the eastern San Fernando Valley, the Santa Clarita Valley and the western San Fernando Valley, according to the National Weather Service. Parts of the San Francisco Bay Area could also get highs of up to 102 degrees.

In Death Valley National Park, lower elevations could get high temperatures up to 113 degrees this weekend, making for “dangerously hot conditions for early October," the NWS said in an alert.

The weather service also warned people in Arizona of a “major heat risk” through the weekend, with temperatures up to 115 degrees in parts of the state. Some parts of neighboring Nevada could reach up to 110 degrees over the weekend, as well.

Meanwhile, on the opposite coast, temperatures climbed into the mid-90s in parts of Florida that were recently ravaged by Hurricane Helene, including Tampa, Fort Myers and St. Petersburg. 

Denise Chow

Denise Chow is a science and space reporter for NBC News.