Water temperatures off Florida may have broken world record

A sweltering summer that has shattered heat records worldwide and in Florida continued this week when a buoy station off the Florida Keys recorded a water temperature that, if confirmed, would set the record for the warmest seawater temperature ever recorded on the planet.

The buoy in Manatee Bay, a largely enclosed body of water north of Key Largo, captured a stunning 101.1-degree Fahrenheit reading at 5 feet deep Monday night, according to preliminary data from the National Data Buoy Center.

That would beat the previous record of 99.7 degrees, which was recorded in Kuwait Bay in the Persian Gulf in 2020.

”If you climbed in the water there, I’m pretty darn sure it would have felt like you’re in a hot tub,” said Jeff Masters, a hurricane scientist formerly with the National Oceanic and Atmospheric Administration.

The waters in that area have warmed so much because calm wind and wave conditions have created perfect conditions for warm, shallow water to move more slowly and heat up under the hot sun.

And the coral bleaching crisis in the Florida Keys elevated to new heights this week, when the prolonged hot water prompted an emergency harvest of more than 1,500 corals from offshore nurseries. Researchers are now sheltering the corals in temperature-controlled tanks at the Keys Marine Laboratory on Long Key, where they could remain for months.

At least 11 other buoys measuring water temperatures around Everglades National Park logged temperatures higher than 96 degrees Monday. On Sunday, the same Manatee Bay buoy recorded a sweltering 100.2 degrees.

Masters said these surrounding measurements show that the reading should be taken seriously, though it’s still uncertain what the exact water temperature might have been Monday night.

“Maybe not 101 — maybe only 99,” he said. “I think it was probably at least 99 in that water.”

There is some nuance with the measurement: Manatee Bay can have a lot of floating organic material, which could potentially impact the reading’s accuracy. So unless there’s photo proof that there wasn’t debris around the buoy, the record would be hard to verify, Masters said.

“That would be my No. 1 question,” he said. “Was there a lot of seagrass present that was absorbing a lot of sunlight skewing the reading?”

Michael Lowry, a meteorologist for WPLG Local 10 News in Miami, wrote in a tweet that Monday’s buoy reading may not have even set the highest record in Manatee Bay. He said a reading in August 2017 hit 102 degrees Fahrenheit, citing historical records maintained by the South Florida Natural Resource Center. The Tampa Bay Times was unable to independently verify that data.

Masters said we may never get an official confirmation of any buoy data. The National Oceanic and Atmospheric Administration doesn’t keep official water temperature records, he said.

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Brian McNoldy, a senior research associate at the University of Miami, said this is because there is no agreement among researchers on a uniform method to measure temperatures, or at what depth they should be recorded.

“Even in the U.S. — and certainly internationally — there’s just a lack of a standard for sea surface temperature,” he said. “When you get down to calling something a record, you start nitpicking.”

McNoldy said the reading isn’t much more than “an interesting data point.”

Coastal water temperatures often fluctuate greatly, and shallow, protected waters in Manatee Bay are no exception, McNoldy said. A couple of cloudy days or a storm blowing through could greatly reduce its surface temperature.

“It’s too small of a region to really influence much,” he said. “If you were actually there, you would not perceive it as actually being open ocean at all.”

Experts are already on alert from abnormally high average water temperatures brought by a marine heat wave in the Gulf of Mexico and Atlantic Ocean. It’s these broader ocean temperatures that can affect hurricane strength and daily weather patterns, McNoldy said.

“That’s more important than the super-hotspot in Florida Bay,” he said.