"Friday’s spring equinox may seem like a quaint notion to those already enduring furnace-like 90-110°F summer heat."
"Multiple all-time March heat records crumpled on Wednesday and Thursday, March 18-19, as one of the most extreme weather events in world history blitzed the Southwest U.S. and far northwest Mexico with unprecedented March heat. Many locations have been hit with their earliest 100-degree-Fahrenheit weather on record, smashing all-time March and even April records, and temperatures are expected to soar even higher in some areas Friday and Saturday as the heat crescendoes.
Update: On Friday, March 20, eight states set an all-time March heat record, and the U.S. national March heat record was set or tied for the third consecutive day (see Bluesky post below).
The extreme ridge of high pressure responsible for the heat wave peaked on Thursday, reaching an intensity of about 3.5 to four standard deviations above normal (for those technically savvy, the 500-millibar height maxed out at about 598 decameters). Even though this ridge is now slowly weakening, more pulses of record March heat could erupt from the Desert Southwest to Texas Tuesday through Thursday.
Both Mexico and the United States have already experienced their hottest March readings on record this week. On Wednesday, Mexicali set a March record for Mexico with 40.9 degrees Celsius (105.6°F), and on Thursday, that new record was smashed with 42.5 degrees Celsius (108.5°F) at Hermosillo. Meanwhile, the U.S. March record of 108°F set at Rio Grande City, Texas, on March 30, 1954, was tied at North Shore, California, on Wednesday, and then broken on Thursday with 110°F at Martinez Lake, Arizona, then broken again on Friday with 112°F at Martinez Lake, Arizona, Fort Yuma, Arizona, Buttercup, California, and Squaw Lake, California."
Jeff Masters and Bob Henson report for Yale Climate Connections March 20, 2026.
