Phoenix sees jump in annual heat streaks
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Phoenix and other Arizona cities have seen an increase in heat streaks in recent few decades.
The big picture: Many U.S. cities now have more heat streaks on average each year compared to 1970, a new analysis finds.
Why it matters: Prolonged heat — as Phoenix and much of the U.S. have experienced this summer — is particularly hazardous to human health.
- Extreme heat's effects on the body tend to be cumulative, and warm nights offer little reprieve for those without air conditioning.
- Multi-day heat streaks are also challenging for power grid operators, given all the energy-intensive A/C use.
By the numbers: The average number of annual extreme heat streaks rose between 1970-2024 in 80% of the 247 U.S. cities analyzed in a new report from climate reasearch group Climate Central.
- The nearly 200 cities with an increase now have two more annual heat streaks on average.
- Phoenix, Tucson and Yuma were on the higher end, averaging three more heat streaks year, while Prescott got an extra two annually and Flagstaff gained one.
How it works: Climate Central defines an "extreme heat streak" as three or more days in a row with maximum temperatures over the 90th percentile of a given location's daily max temperatures during the 1991-2020 period.
- "Across the 247 cities analyzed, this temperature threshold ranged from 66°F in Juneau and Anchorage, Alaska to 100°F in Yuma, Arizona," per the report, which is based on publicly available NOAA data.
Zoom in: Some areas, like Nashville and Raleigh, now have a whopping five more heat streaks on average per year.
- A few places, like Myrtle Beach, South Carolina, and Sarasota, Florida, have fewer compared to 1970.
Between the lines: Climate change is making extreme heat more intense and more frequent, studies have shown.
- Many urban neighborhoods suffer from the "urban heat island" phenomenon, where buildings, roads and other structures trap heat, making it even hotter.