Trails Closed, Hikers Rescued, and Dying Superblooms: The Toll of the Southwest's Record Heat Wave

A historic heat dome is rewriting the record books across the American Southwest and beyond, forcing trail closures at some of the country's most visited national parks and recreation areas while presenting a growing list of dangers for residents and spring break travelers. As of today, meteorologists expect the dome to begin weakening this week, but temperatures in the Desert Southwest are likely to remain well above normal even as the worst of the heat fades.

Records Falling Every Day

This heat wave has been extraordinary by any historical measure. Martinez Lake, Arizona, recorded 110 degrees Fahrenheit on Thursday, March 19, setting a new all-time national record for the hottest March temperature ever documented in the United States. That record had stood since 1954. It did not last long. By Friday, four stations across Arizona, New Mexico, and California had each reached 112 degrees, pushing the national March record higher for the fourth consecutive day.

Phoenix recorded 105 degrees on both Thursday and Friday, setting its all-time March high twice in 48 hours. The city had only reached triple digits in March four times in its recorded history before this week, and three of those occurrences happened within days of each other. On Wednesday, Phoenix hit 102 degrees, its earliest triple-digit day ever, more than a month ahead of when the city typically first hits the century mark. In a normal year, Phoenix does not reach 100 degrees until around May 10.