Phoenix is known for heat, but it’s never been this hot in the Valley before. The National Weather Service confirms 2024 was Phoenix’s hottest year on record.
National Weather Service Meteorologist Ryan Worley said the record wasn’t even close. The year-round average temperature last year topped the previous record by 1.3 degrees.
"The average temperature throughout the year was 78.6 degrees, which bests the previous record set both in 2017 and 2020," Worley said.
The past month was the warmest December in Phoenix history — the average temperature for the month was more than 6 degrees above normal. June, September and October this year each also broke monthly temperature records.
This year, Phoenix shattered last year’s record for most days with high temperatures at or above 110 degrees. Phoenix typically sees 21 days per year above 110, but 70 days this year passed the 110 mark.
This summer the Valley also endured its longest-ever streak of consecutive days above 100 degrees. 113 days in a row brought triple-digit temperatures. The previous record had been 76 days.
And nighttime temperatures this summer brought little relief. Phoenix set another record this year for most nights with low temperatures in the 90s. On average, seven nights per year in Phoenix won’t cool below 90. In 2024, 39 nights stayed that warm.
“It’s prolonged periods, record-breaking periods of extremely high temperatures. And that is difficult on people’s health, it’s difficult on the economy, it’s difficult on the environment. I mean, these are widespread impacts,” said Kaitlyn Trudeau, senior research associate for climate science with the climate research organization Climate Central.
Extreme nighttime temperatures prompted Phoenix city officials to keep some public cooling centers open overnight for the first time this year. Extended-hour heat relief sites had more than 35,000 visits from May to October, the city reports.
And amid unprecedented heat waves that lasted later into the fall than usual, city officials decided to keep some cooling centers open weeks beyond their scheduled closing dates.
This year’s extreme heat led to at least 466 deaths in Maricopa County, according to the county public health department. More deaths remain under investigation.
Trudeau said the extreme temperatures of 2024 point to an alarming climate change trend. She said 2024 is likely to be confirmed as the hottest year on record worldwide. But she said Phoenix stands out.
“Phoenix has been kind of this epicenter in the U.S. of just truly remarkable heat, and it’s not just that it’s hot, it’s that it’s prolonged, and I think that’s what’s really scary,” Trudeau said.
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