A buoy in Manatee Bay, Florida, showed an ocean temperature reading of over 101 degrees Fahrenheit on Monday evening, the latest sign of record heat in the coastal waters.
The buoy is owned and operated by the Everglades National Park, part of the National Park Service, and the data from that buoy is recorded and distributed by the National Data Buoy Center, a division of the National Oceanic and Atmospheric Administration. The temperature was recorded about five feet below the surface off South Florida's east coast.
"This data is consistent with high water temps seen across Florida Bay in recent weeks," Allyson Gantt, communications director for Everglades and Dry Tortugas National Parks, told CNBC. "This station is reporting one of the highest temperatures currently, but it's only a few degrees higher than water temperatures at nearby stations, so we have no reason to doubt the measurement."
It's a critically hot reading for an ocean, and is especially concerning for the coral reefs in the area, which typically thrive at temperatures between 73 and 84 degrees, according to NOAA. And while it may be an all-time high, the comparison to other top readings is tricky because of how it was recorded.
The existing record for the hottest ocean surface temperature is 99.7, which was reached in Kuwait Bay in the Persian Gulf. Jeff Berardelli, Florida WFLA News Channel 8's chief meteorologist and climate specialist, said it's unclear if Monday's reading will be counted as a world record.
"These buoys that are inside Florida Bay — so that's to the north of the Florida Keys and to the South Florida peninsula — they're all in very shallow, murky, dark water," Berardelli told CNBC. "Because it's murky, and because it's contaminated with sediment, the water temperatures are reflective of the fact that darker surfaces absorb more heat."
Berardelli said the unique qualities of the area mean that "it's not really comparable to most water measurements, which are in more clear water that may have a little bit more water movement — like tidal movement."
Complicating maters further, he said, "there are no official records that are kept on water temperature." A spokesperson for the World Meteorological Organization told CNBC that the group's weather and climate extremes archive doesn't currently track sea surface temperatures.
Nevertheless, recent readings in South Florida have been extreme. Berardelli said two other sites in the Florida Keys recorded temperatures of 98 or higher, "which substantiates the fact that this sensor was likely either correct or it was off by a degree, but even if it's off by a degree, it's still close to a world record."
The heat, which has penetrated Florida's coastal waters for the past several weeks, presents major environmental concerns, said Phanor Montoya Maya, a marine biologist and the restoration program manager for the nonprofit Coral Restoration Foundation.
"If water temperatures remain above 84 Fahrenheit for a significant period, corals will begin to experience stress and will start to bleach," robbing them of nutrition they need to survive, Maya said in an emailed statement.
Corals can recover from bleaching when temperatures return to normal levels.
"Water temperatures are now so elevated that it is likely becoming an existential threat for even the hardiest of corals on Florida's Coral Reef," Maya said. "Unfortunately, the water is now so hot that we are seeing some corals die as a result of heat stress."
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