Orlando’s hottest of hot days will triple by 2052, study finds – Orlando Sentinel

Think of the doggiest days of summer, those most daunting for venturing beyond air conditioning, and then imagine what global warming will bring in three decades.

Seven times a year now, on average, the heat index in Orlando hits nearly 108 degrees. Thirty years from now, it’s expected to feel that hot for 22 days a year.

That’s the prediction from the First Street Foundation, a nonprofit research and technology group that on Monday released its 30-year temperature outlook. The group focuses on evaluating fire, flood, heat and other risks from climate change.

“The United States faces a challenging problem of adapting to extreme heat that is getting worse over time,” the foundation says in its report, which presents the nature’s future heat picture at “hyper-local resolution.”

Florida, the Sunshine State, will lead the nation with the greatest increase with “hot” days by 2052, the group says.

The hottest seven days of summer in Orlando on average hit nearly 108 degrees on the heat index utilized by the National Weather Service, which blends temperature and humidity to convey what a temperature feels like and what risks it may pose to human health.

In cities across Florida, the seven hottest days of the year — which the foundation refers to as local hot days — are within a few or several degrees of Orlando’s nearly 108 heat index degrees.

Similarly, the 30-year outlook by First Street Foundation shows that other Florida regions will experience three weeks of equally hot days, plus or minus a few or even many days.

In Miami-Dade County, for example, the average heat index temperature of seven hottest days of the year is 105. In 30 years, the county will deal with 29 of those days, First Street Foundation calculates.

“This means that what would have hypothetically been the hottest week of the year in 2023, becomes the hottest month of the year in 2053,” the foundation’s report says. “Florida is expected to see the greatest increases in Local Hot Days in 30 years relative to today.”

Florida and some of the Southeastern states abutting the Gulf of Mexico also stand out for the projected increase in the number of days exceeding 100 heat index degrees in the coming 30 years.

Miami-Dade will have the biggest jump, according to foundation calculations, climbing from 50 such days to 91.

Florida has 18 of the 20 counties in the US expected to have the greatest increase in 100 heat index degree days.

Along with Miami-Dade, the top 10, in order, are: Broward from 55 days to 95 days; Palm Beach from 55 to 94; DeSoto from 69 to 106; Manatee from 70 to 106; Okeechobee from 58 to 86; Glades from 73 to 109; Martin from 60 to 96; Indian River from 44 to 80; and St. Lucie from 57 to 92.

Orange County will see an increase from 61 to 93, with Seminole from 50 to 72, Lake from 58 to 90 and Osceola from 64 to 97.

There is a tiny sigh of relief to be found in the foundation’s report, which adds to the group’s lineup of climate-change considerations available at firststreet.org and is called “The Sixth National Risk Assessment: Hazardous Heat.”

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Florida will have many more hot days but not necessarily hotter days, with a notable exception of the state’s southwest coast.

First Street Foundation calculations show that 8 million residents in 50 counties will experience heat index temperatures above 125 degrees on at least one day in 2022.

By 2053, 107.6 million people in 1,023 counties will experience that extreme heat.

A majority of those counties cover a region labeled by the foundation as the “extreme heat belt,” extending “from the Northern Texas and Louisiana borders to Illinois, Indiana, and even into Wisconsin.”

“The interesting thing to us was there is a protective effect of being close to the water which almost limits the ceiling of heat index values,” said Jeremy Porter, who leads research at First Street Foundation.

“The models were pretty clear that Florida is going to hit more days above 100, days like you had in these past few weeks,” Porter said. “But because of the water there is sort of physical limit on how hot temperatures can get.”

kspear@orlandosentinel.com

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