Comment A historically severe September heat wave is baking the West, breaking hundreds of records, endangering public health and pushing California’s power grid to the limit. Some records have been broken by wide margins as the hot air mass exacerbates fire danger in the drought-stricken region. California’s Independent System Operator (ISO) says the state’s power grid is under severe stress and spin-off outages could occur unless consumers cut back on energy use even more than they have since the heat wave began last year. since a week. “This is an extraordinary heat wave we’re experiencing, and efforts by consumers to lean in and reduce energy use after 4 p.m. The agency, which has declared an energy emergency alert, is predicting an all-time high demand of 51,033 megawatts in Tuesday afternoon, surpassing the previous record of 50,270 megawatts set on July 24, 2004. The ISO urges residents to “pre-cool” their homes to 72 degrees on Tuesday and Wednesday mornings, then turn the thermostat down to 78 degrees during peak demand hours between 5 p.m. and 9 p.m. He has requested such reductions on seven consecutive days. During a news conference about the September heat wave, California Gov. Gavin Newsom (D) on Aug. 31 said that “we live in a time of extremes.” (Video: The Washington Post) The heat is historic in both duration and intensity, as evidenced by the long-term monthly and all-time records that continue to be broken. In Sacramento, the downtown area hit 113 degrees Monday, just one point below the all-time high set on July 17, 1975, and four points higher than the previous September record. Records there date back to 1877. On Tuesday afternoon, Sacramento is expected to jump to 115 degrees, which would be both a monthly and all-time high, as well as just the 11th time in the last 145 years that the city has reached 112 degrees or higher. Fairfield, California, on the northeast side of the Bay Area, set an all-time high Monday at 117 degrees. About 42 million Americans are under extreme heat warnings, including most of California, northeastern Arizona and neighboring southern Nevada. The Great Basin, southern Idaho and western Utah are under heat warnings. “Extreme heat will greatly increase the potential for heat-related illness, particularly for those who work or participate in outdoor activities,” the National Weather Service wrote. “[There is a] very high risk of heat stress or disease for the entire population.” Maximiliano Herrera, a global weather historian, called this the “worst September heat wave in Western US history” on Twitter over the weekend. Extreme heat also fuels the risk of fast-moving wildfires. Red flag warnings – indicating dangerous fire weather – cover all of Montana except northern Idaho, much of Oregon and northern and eastern Washington. A series of large wildfires have broken out in the past week in California, Oregon, Idaho and Montana. The fast-moving Mill Fire that broke out Friday in Northern California killed two people and injured three. On Monday, two people died and another was injured in the Fairview Fire, which started near the town of Hemet, which is about 75 miles southeast of Los Angeles in Riverside County.
Warmer weather is possible for some on Tuesday The heat will reach a chilling crescendo on Tuesday as a stagnant high-pressure ‘heat dome’ peaks overhead. It repels clouds and rain and diverts the jet stream north into Canada. Below that, sinking air and unrelenting sunshine deliver some of the hottest weather ever seen in the Golden State. Outside the deserts, the worst of these have been concentrated in California’s Central Valley. The National Weather Service specifically predicts Sacramento will reach an all-time high of 115 degrees on Tuesday. In addition to the all-time record, that temperature would also obliterate what until Monday was Sacramento’s monthly record for September of 109 degrees. Some places in the Central Valley could approach 118 degrees. “It still looks like the ongoing record heat wave will peak today, but dangerous heat will likely remain through the end of the week,” the Weather Service office in Sacramento wrote Tuesday. The heat is driving the spine of California up to the Bay Area and Southern California as well. San Francisco Airport is expected to hit 99 degrees on Tuesday. Although surprisingly warm, September 6, 2020 was three degrees warmer. Regardless, it’s still two dozen points higher than the average of 75. Los Angeles will spend the next few days in the mid to upper 80s, but will top out around 90 on Friday. Keep in mind it’s at the airport though – just a few miles inland, highs will hover around 100 to 105 degrees. Death Valley, Calif., has hit 124 degrees three times in the past five days. He could flirt with 126 on Tuesday, which would tie the world record for September. The heat has also spilled eastward, bringing weather to Denver, with record highs in the 90s near 100 predicted through Thursday. Salt Lake City — which has set a September record high of 104 on Monday — will continue to hover in the low 100s. The heat will gradually begin to subside on Thursday. Closer-to-average temperatures will return to much of California over the weekend, although temperatures will remain somewhat above normal in the Pacific Northwest and Northern Rockies. At that time, moisture from Hurricane Kay in the Pacific southwest of the Baja Peninsula could begin to jet northward, lowering temperatures and possibly bringing some beneficial precipitation to Southern California and further north. However, its specific effects on the region are highly uncertain, and it could also increase the chance of dry lightning that could increase fire danger.
Climate Change Connection While extreme heat phenomena are not caused due to climate change, the human impact on our atmosphere is making them more frequent, intense and prolonged. It already drives high-end events in record territory. Breaking records by wide margins, the heat wave bears shades of the unprecedented events that scorched the Pacific Northwest in June 2021 and the UK in July, both of which scientists concluded would have been nearly impossible without human-made climate change. In the state, last week more than 1,141 warm weather records were set in the United States compared to just 36 cold records. If climate change were not a factor, these extremes would roughly balance out. From California to Montana, hundreds of heat records have been set since August 30, and dozens more are at risk in the coming days. In addition to calendar day records, many locations have set monthly records and even all-time records (warmest temperature observed in any month). We highlight some of the most important ones here:
Downtown Sacramento set a September record high of 113 Monday, just one point shy of the all-time high of 114 set on July 17, 1925. Stockton (112), Vacaville (115) and Marysville (113) also set September record highs in Central California Valley. Fairfield, Calif., about 40 miles northeast of San Francisco, hit a record high of 117 degrees Monday — three points above the previous record. Livermore set an all-time high at 116. Salt Lake City has broken the previous September record three times in the past week. It hit 104 on Monday, 103 on Saturday and 102 on Thursday. The previous monthly record was 100. It has hit at least 100 five times this month. Before 2022, it had done so only three times during September dating back to 1928. Reno, Nev., set a September record high of 104 on Sunday after tying the previous monthly record of 102 on Friday. San Diego recorded an all-time low on Sunday, dropping to just 78 degrees. Burbank, California recorded its lowest temperature ever on Sunday, dropping to just 82 degrees. Wednesday set a record high temperature for August at 112 degrees. Las Vegas set a record high September minimum temperature of 87 degrees on Sunday. Casper, Wyo., set September record 100 Sunday. On Saturday, the low temperature in Death Valley of 102 degrees tied for the highest minimum temperature ever recorded worldwide for September. Death Valley has topped 120 degrees seven straight days, setting calendar day records of 123 on Wednesday, 124 on Thursday, 124 on Friday, 122 on Saturday and 124 on Sunday. It has set a new September record for most days reaching at least 120. On Saturday, several locations in the Mountain West set September records, including Great Falls (102), Bozeman (10o) and Butte (96) in Montana, and Pocatello (102) and Idaho Falls (99) in Idaho. The heat even soared in western Canada on Friday, where the village of Lytton set a British Columbia September record of 103.3 degrees (39.6 Celsius). Fresno, Calif., tied its September record on Friday, climbing to 111 degrees. Redmond, Ore., set a September record high of 106 on Friday.
