Nearly all of South Florida is under an excessive heat warning Tuesday, the first one ever issued for Palm Beach County, forecasters said.
Highs will reach the mid- to upper-90s by afternoon, while the heat indices or “feels-like” temperatures will reach 116 degrees in some places, according to the National Weather Service in Miami.
The warning will expire at 7 p.m., forecasters said. Tuesday night will remain “warm and humid,” with temperatures in the upper 70s to 80s.
Tuesday’s broken record is yet another reminder of how unusual South Florida’s stifling heat has been this year, not only in terms of how high temperatures have gotten, but how long the heat wave has endured, and will continue to endure.
“We really don’t have too many excessive heat warnings in general,” said Cameron Pine, a meteorologist with the National Weather Service, “but this year has been more than oppressive and abnormal compared to other years.”
Tuesday’s warning is also the first excessive heat warning issued for Glades and Hendry counties.
The National Weather Service has issued heat advisories for South Florida nearly every day this summer; that means feels-like temperatures have reached at least 108 degrees in Broward and Palm Beach counties and 105 degrees in Miami-Dade for at least two hours.
To meet the criteria for an excessive heat warning, the hot weather must be even more severe: in Broward and Palm Beach counties, the feels-like temperature has to reach at least 113 degrees for at least two hours, while in Miami-Dade, it has to exceed 110 degrees.
Forecasters usually issue an excessive heat warning once every few years, Pine said, not several times in a month and a half.
Palm Beach County also has slightly more cloud cover and rainfall than more southern counties, which normally help to combat the heat, but have been no match for the high sea-surface temperatures and low-level moisture in the atmosphere.
Meanwhile, a dry airmass moving toward South Florida from the Bahamas is keeping rain chances low and adding to the insulation “so that maximum temperatures can reach maximum potential,” Pine said.
South Florida has already seen an increase in emergency calls due to heat-related illness. Palm Beach County warned residents in a news release Tuesday to stay safe by limiting time outside, staying hydrated and out of the sun, and never leaving children or pets in a parked car.
The heat will remain, unrelenting, for the remainder of the week. Tuesday will likely be the hottest day, Pine said, but Wednesday will likely meet the same criteria for a heat advisory or excessive heat warning.
The weekend might bring some brief relief as cloud cover and rain chances increase due to moisture associated with a tropical disturbance, though the extent of that relief will depend on how far north the moisture extends.
Excessive heat has become a “permanent fixture” of the region’s weather, Pine said, rather than an outlier. “There’s no real relief in sight.”