An extraordinary heat wave is enveloping portions of the western United States as October begins, with record-setting temperatures and ongoing heat advisories expected to persist throughout the weekend.

Weather experts predict that this intense late-season heat wave will result in mild to severe heat dangers in different areas of the Southwest during the week and into the weekend. The National Weather Service announced that around 39 million individuals in the area were under heat advisories on Wednesday.

Excessive heat alerts have been prolonged for regions close to major metropolitan areas such as Las Vegas, Phoenix, San Francisco, and Los Angeles. Portions of Arizona, California, and Nevada are forecasted to experience temperatures that are 10 to 25 degrees higher than usual.

“Many areas will face significant to extreme heat effects over the next few days, with temperatures expected to reach between 90°F and 110°F each afternoon, potentially breaking previous high-temperature records,” the weather service warned on Wednesday.

The extreme heat is attributed to a heat dome, a potent high-pressure system that traps warmth in a particular area, preventing cooler air from entering. AccuWeather meteorologist Isaac Longley informed YSL News that this ridge of high pressure has been stable over the Southwest.

“This is certainly an impressive duration of heat, especially for certain locales and cities throughout the West and Southwest,” Longley commented. “It’s not moving. There is no dip in the jet stream to bring in cooler or more comfortable weather to the Southwest and areas along the West Coast.”

Longley also mentioned that the heat dome is “large,” affecting other locations like Denver, where unseasonably warm conditions prevail. Meteorologists anticipate that numerous heat records will likely be established throughout the weekend across the Southwest and West Coast.

This early-autumn heat wave comes on the heels of a summer filled with extreme heat across both the western and eastern United States. Last month, the National Oceanic and Atmospheric Administration noted that the summer of 2024 ranked as the fourth hottest summer recorded in the U.S.

States like Arizona and California experienced their hottest summers on record, according to NOAA. “Due to climate change, summers are becoming hotter across much of the Western U.S., as the frequency and duration of heat waves are increasing,” said the NOAA’s Climate Prediction Center.

Phoenix Suffers with High Temperatures for a Full Week

Having just experienced its hottest summer on record, Phoenix found no respite in September, enduring continuous high temperatures over 100 and even reaching 110 degrees throughout the month.

The temperature records continued into October when both Phoenix and Yuma hit 113 degrees on Tuesday, marking the hottest October day ever recorded in Phoenix. Before this week, Phoenix had never reached or surpassed 110 degrees in October, according to forecasts from the weather service.

Tuesday marked the eighth consecutive day of setting, tying, or breaking temperature records in Phoenix, as reported by the Arizona Republic, a part of the YSL News Network. The heat records persisted on Wednesday, with reports of temperatures reaching 108 degrees, exceeding the previous record of 107 degrees set in 1980.

The weather service has extended an excessive heat warning through the weekend, signaling that “record-breaking daily high temperatures are projected to continue,” the agency stated on Wednesday. Temperatures are expected to range from 105 to 112 degrees in the lower desert regions.

Record highs in California

AccuWeather reported that temperatures along parts of the California coast reached seasonal highs. San Francisco saw temperatures rise to 94 degrees on Tuesday, the hottest day for the city since 2022, according to the weather service.

“The temperature reached 94 degrees in San Francisco yesterday, with similar conditions expected today,” the weather service for San Francisco reported on Wednesday. “In October, we have only reached this mark 15 times over the last 150 years.”

The weather service has also extended its excessive heat warning for the inland sections of the Bay Area, Central Coast, and San Francisco until late Thursday. Several daily temperature records were tied or broken in the area on Wednesday, with San Jose hitting 106 degrees, surpassing its previous record of 96 degrees set in 1980 and 2012, according to the weather service.

Los Angeles is expected to continue experiencing high temperatures through Thursday, with the hottest areas likely reaching between 100 and 106 degrees, as per the weather service. Many records were already observed on Tuesday throughout Los Angeles County, with some areas experiencing triple-digit temperatures.

Throughout the week, temperatures are expected to be 5 to 10 degrees above the historical averages, according to AccuWeather.