Phoenix's summer weather is lasting longer and getting hotter
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Summer temperatures are hanging around longer in the Valley and nationwide compared with in the early 1970s, a new analysis finds, as climate change affects the four seasons.
Why it matters: Temperatures staying high for longer periods can increase cooling demand (and cost) and prolong the risk of heat-related illnesses.
- Longer summers also elevate the risk of wildfires by drying out vegetation and soil, creating more fuel for blazes.
Zoom in: Summer temperatures are lasting an extra eight days on average in Phoenix compared to 1970, according to a new report from Climate Central, a climate research group.
- In Tucson, warm weather's sticking around an extra 24 days — one of the most significant increases among U.S. cities.
How it works: Climate Central's analysis is based on NOAA data and reflects the last date each year with highs equal to or greater than historical summer-like temperatures.
- The group defined "summer-like temperatures" as the 75th percentile of daily highs during the 1991-2000 climate normal.
Flashback: Last year, extreme heat continued in the Valley into fall with the National Weather Service recording temperatures above 110° in October for the first time on record.
- Previously, the latest we'd ever seen 110° was Sept. 19, in 2010.
State of play: Summer-like temperatures aren't just lasting longer — they're also getting hotter.
- So far, this September's temperatures are about a degree above average and each of the past three Septembers have seen above-average temperatures, National Weather Service Phoenix meteorologist Katherine Berislavich told us.
- Last year, September temperatures were 5.4 degrees higher than average, she said.
By the numbers: Heat-related deaths in Maricopa County appear to be down this summer compared with last, though deaths are still trending much higher than a decade ago.
- The county's Office of the Medical Examiner has confirmed 133 heat-related deaths and is investigating 385 additional deaths as of Sept. 13.
- At the same time last year, the county confirmed 222 deaths and was investigating 413.
- In 2015, there were 84 total heat deaths for the year. The number of deaths has trended up at a fast clip since then.
- Last year, 608 people died, a slight decrease from the record set in 2023 of 645.
Zoom out: Summer temperatures are lingering compared with 1970 in just over 90% of the 246 U.S. cities analyzed by Climate Central.
- Among cities with lingering heat, summer temperatures are lasting an extra 10 days on average.
What they're saying: "Research suggests that high future levels of heat-trapping pollution would cause summers to continue to stretch longer and later in the coming decades — putting health, ecosystems and agriculture at risk," per the report.
What's next: We are likely done with 110-degree days, but the Climate Prediction Center is still forecasting higher-than-normal temperatures in Phoenix for the weeks and months ahead, Berislavich said.