An unusually prolonged autumn heatwave is currently sweeping through California, with over 35 million residents facing the risk of extreme high temperatures. This abnormal October heatwave has caused temperatures to soar above 40°C (104°F) in multiple locations across the state, breaking dozens of historical temperature records for this time of year.
This heatwave is influenced by a strong high-pressure ridge in the upper atmosphere (Heat Dome) and the compressional heating effect, extending its reach from the Bay Area in the north to the US-Mexico border, setting new October records in many areas.
The National Weather Service in Los Angeles confirmed that four counties in Southern California (Los Angeles, Ventura, Santa Barbara, and San Luis Obispo) have broken 14 high-temperature records. In downtown Los Angeles, there have been rare consecutive days with temperatures exceeding 38°C (100°F) in October.
During this period, daytime temperatures in many California cities have been 7 to 10°C higher than the seasonal averages. Cities like downtown Los Angeles, Woodland Hills, Bakersfield, San Diego, and Sacramento have all experienced temperatures reaching or surpassing 40°C.
As a result of the Heat Dome coverage, nighttime temperature drops in major cities have been very limited, subjecting residents to prolonged heat exposure throughout the day.
The US meteorological department has issued extreme heat warnings, urging the public to guard against heatstroke, reduce outdoor activities, and opening local cooling centers for residents who have difficulties escaping the heat at home.
Weather forecasts indicate that this extreme heatwave is expected to continue until Thursday (the 8th), after which temperatures are anticipated to gradually decrease.