Whether it’s climate change or not, a heatwave like this in mid-June in the western United States had never happened before. The hot air started pumping from Sunday 13 June and has never stopped. Indeed, forecasts say it will last at least another five or six days. California, Nevada, Arizona, Colorado and Utah could still see extreme temperatures for several days; the peak of the heat wave, which will also affect Montana and Wyoming, is expected between Thursday and Friday, when numerous daily records, many monthly records and possibly some all-time records are at risk as well. About 50 million people are on high alert for the heat.
Las Vegas reached 45.6 ° C, Phoenix could hit 46 ° C. The world record for the highest temperature ever recorded, Death Valley’s 54 ° C in 2020, could be surpassed. For now at Zabrinskie Point we are ‘just’ at 51 °. Up to now 49.4 ° C have been reached in Needles in Calfiornia, 48 ° C in Ocotillo, 45 ° C in Safford Arizona, 44 ° C in Tucson (Arizona), 1987 record beaten in Helena (Montana) with 40 ° C, in Billings (1959) with 39.5 ° C. All-time record in Salt Lake City with 41.7 ° C which equaled July 1960 and July 2002.
The heat wave is due to a strong anticyclone which is fed by a very hot air mass from the desert. These air masses are characterized by a rather low density, they are stable and also very dry; they have the potential to be significantly heated by subsidence.