A historic March heatwave has shattered high-temperature records across the US south-west, with California, Nevada and Arizona experiencing temperatures 25-35F above normal. The National Weather Service (NWS) issued heat warnings on Thursday, warning of extremely rare March heat and a high risk of heat illness.
In California, the desert community of North Shore reached 108F (42.2C) on Wednesday, tying the highest March temperature ever recorded in the US, a mark first set in Rio Grande City, Texas, in 1954. Palm Springs is expected to hit 108F on Thursday, with heat alerts in effect through Sunday. Downtown Los Angeles reached 94F (34.4C), beating its previous daily high for 18 March of 87F (30.5C) set in 1997.
Arizona and Nevada also saw record-breaking heat. Phoenix set a record-high overnight low for 19 March of 69F (20.5C), with daytime highs expected to reach 105F. The NWS noted that the average first 105F day in Phoenix occurs on May 22. Las Vegas set a March record on Wednesday, and Reno experienced record-setting warmth expected to peak on Friday.
The NWS warned that daily records would be broken each day through Sunday, with a peak expected on Friday. Temperatures are forecast to cool next week, with Los Angeles dipping to about 80F. Western national parks, including the Grand Canyon and White Sands, urged visitors to check forecasts and avoid strenuous activity during the hottest part of the day, from 10am to 4pm. Hiking trails at Lake Mead national recreation area were closed due to the heat.
