Human-amplified climate change is making it more likely that extreme heat to lasts longer into fall, as record-breaking temperatures for the month of October blanket much of the western U.S.
An unprecedented late season heat wave is in effect in the West, with October temperatures broken in major cities, several of which are still experiencing triple-digit heat.
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On Tuesday, Palm Springs reached 117 degrees Fahrenheit; Phoenix hit 113 degrees while Tucson got up to 105 degrees.
Elsewhere in California, San Jose broke its daily record at 100 degrees; Oakland reached 96 degrees; Napa hit a daily record at 99 degrees; and downtown San Francisco reached 94 degrees, the hottest October temperature in the city in two years.
Some regions are expected to experience even hotter conditions on Wednesday. Heat alerts have been issued throughout California, Arizona and Nevada. Excessive heat warnings are also in place for San Francisco, Las Vegas and Phoenix, and a heat advisory has been issued in Los Angeles.