Summer Heat in the Valley: A Rising Trend
For many Valley residents, summer forecasts that read "hot" almost every day have become routine.
Historical Temperature Records
From 1991 through 2020, Phoenix averaged 111 days per summer with temperatures of 100°F or higher, the National Weather Service reports. This year the city has already recorded 90 days of triple-digit heat. In 2020 Phoenix set a modern-era mark with 145 such days — nearly 40% of the year.
Long-term Climate Data
Looking farther back, Phoenix’s long-term totals are staggering. Since the early 1900s the city has experienced 11,410 days of at least 100°F, according to AccuWeather — the most for any major U.S. city and equal to more than 31 years of consecutive 100-degree days.
Climate and Environmental Factors
The region’s climate helps explain the numbers. Situated in the Sonoran Desert, Phoenix receives hot air from the south that stays warm as it settles into the Valley. Monsoon rains normally offer brief relief, but this summer monsoon activity has been limited.
Extreme Temperatures and Trends
The heat often climbs well beyond 100°F. Over the past ...