Record Heat Wave Shatters March Records in Southwest US

A record-breaking heat wave swept across the southwestern United States in late March, shattering temperature records in at least 14 states and affecting nearly a quarter of the country. The event, driven by a persistent high-pressure system, brought summer-like conditions to the region during the first days of spring, with temperatures reaching 112 degrees Fahrenheit in parts of Arizona and California on March 20.

The heat dome, as meteorologists describe the atmospheric pattern, trapped warm air over the area for more than a week, compressing it downward and preventing cooler air from mixing in. This system, unusually strong for the season, caused skies to remain clear and air to stay dry, exacerbating the warmth. Weather stations in Yuma, Arizona, recorded a high of 109 degrees that day, 28 degrees above the historical average, while nearby sites in Arizona and California tied for the nation's hottest readings at 112 degrees. The wave extended into Texas, where Lubbock saw mid- to upper-90s temperatures for several days, and into Mexico, with Hermosillo setting a March record of 108 degrees.

By midweek, the heat had pushed eastward, breaking daily records in cities including...