A heat wave is affecting parts of the western United States at the beginning of October with record-breaking temperatures and excessive heat alerts expected to continue into the weekend. Around 39 million people in the Southwest are under heat alerts, with temperatures in some areas expected to be 10 to 25 degrees above normal. The hot conditions are caused by a heat dome, a high-pressure system that traps heat and prevents cool air from entering the region.
The heat wave follows an extremely hot summer in both the western and eastern United States, with several states experiencing their warmest summer on record. The National Oceanic and Atmospheric Administration stated that summers are becoming hotter across much of the U.S. West due to global warming, leading to an increase in both the number and length of heat waves.
In Phoenix, the hottest October day on record was reached when temperatures soared to 113 degrees. Records were also challenged in San Francisco, where temperatures reached 94 degrees. Inland portions of the Bay Area, Central Coast, and Los Angeles were under excessive heat warnings, with temperatures expected to be 5 to 10 degrees above the historical average.
The heat wave is expected to continue through the week, with forecasters predicting that more heat records will be set. The persistence of the heat dome and lack of cooler air entering the region are contributing to the prolonged period of high temperatures in the Southwest and on the West Coast.
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