Excessive Heat in Sonoran Desert Natl Monument, Arizona

A retrograding strong ridge of high pressure resulted in temperatures climbing well above normal across the Phoenix area, while a trough was situated to the west along the West Coast. The hottest days in Phoenix during this time occurred on the 20th and 21st as highs topped out at 115 degrees and 117 degrees, respectively. The 117 degree high on the 21st tied the record high for the date. According to the Maricopa County Department of Public Health, 18 heat-associated fatalities occurred during this time.