A water temperature buoy located inside the Everglades National Park in the waters of Manatee Bay hit a high of 101.19 degrees Fahrenheit (38.44 Celsius) late Monday afternoon, U.S. government data showed, while other buoys nearby topped 100F (38C) and the upper 90s (32C).

Normal water temperatures for the area this time of year should be between 73F and 88F (23C and 31C), according to the National Oceanic and Atmospheric Administration (NOAA), which published the findings from the National Data Buoy Center.

The readings add to previous warnings over Florida's warming waters in the southeastern United States as prolonged heat continued to bake other parts of the country.

The growing frequency and intensity of severe weather - both on land and in oceans - is symptomatic of global, human-driven climate change that is fueling extremes, experts in the field say, with current heatwaves expected to persist through August.

Earlier this month, the United Nations' World Meteorological Organization (WMO) said global sea temperatures have reached monthly record highs since May, also driven in part by an El Nino event. The WMO and NOAA say temperatures like those in South Florida can be deadly for marine life and threaten ocean ecosystems.

That can also impact human food supplies and livelihoods for those who work is tied to the water.

As he worked his knife to filet fish hauled into Key Largo on Tuesday, fishing boat captain Dustin Hansel said the catch has been getting "slower and slower" for the past five summers. He's also been seeing more dead fish in waters around Key Largo.

"As far as all of our bay waters, any near-shore waters, everything is super, super hot," Hansel told Reuters.

NOAA warned earlier this month that the warmer water around Florida could supercharge tropical storms and hurricanes, which build more energy over warmer waters. Rising temperatures are also severely stressing coral reefs, the agency said.