Aug 16, 2022 - News

Metro Phoenix could see temperatures top 125°F by 2035, report shows

Counties expected to experience heat indices above 125°F by 2053
Note: Shaded counties are those that will, on average, have 0.5 days or more above a 125F° heat index in 2053; Data: First Street Foundation; Map: Axios Visuals

Maricopa County is one of many counties across the U.S. where the heat index could reach 125°F at least one day a year by 2053.

  • That's according to a hyperlocal analysis of current and future extreme heat events published Monday by the nonprofit First Street Foundation.

Driving the news: The report makes clear where households will be vulnerable to what would now be considered almost unheard-of heat indices, which show how the air feels from the combination of air temperature and relative humidity, Axios' Andrew Freedman reports.

Why it matters: In just 30 years, climate change will result in higher temperatures for longer periods of time in metro Phoenix.

  • The Valley is already grappling with increased numbers of heat deaths and illnesses during the past several summers.

By the numbers: First Street shows that Maricopa County currently sees an average of 83 days a year with a heat index above 100°F. By 2053, we could likely see an average of 100 days with a heat index that high.

  • Right now, we see an average of 29 consecutive days over 100°F, compared to 45 days expected in 2053.
  • Today, the likelihood of a three-plus day heat wave is 55%. In 2053, it will likely be 85% — 30 years ago it was 12%.

Around Arizona: Nearly every county in the state could see temperatures increase at a similar rate in the coming decades.

  • Yuma County is expected to have the longest, hottest summer in 2053, with a projected 71 consecutive days above 100 degrees.

Zoom out: The report, which is based on First Street's peer reviewed heat model, shows that as of now, just 8 million Americans are exposed to "extreme heat" — a maximum heat index of greater than 125°F.

  • However, due to the anticipated warming over the next three decades, that number is expected to balloon to 107 million people.

Go deeper: How cities are tackling extreme heat


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