Weather records for sea water temperature are unofficial, and there are certain conditions in this reading that could disqualify it for a top mark, meteorologists said. But the initial reading on a buoy at Manatee Bay hit 101.1 degrees (38.4 Celsius) Monday evening, according to National Weather Service meteorologist George Rizzuto. On Sunday night the same buoy showed an online reading of 100.2 (37.9 Celsius) degrees.

The fact that two 100 degree measurements were taken in consecutive days gives credence to the readings, McNoldy said. Water temperatures have been in the upper 90s in the area for more than two weeks.

There aren’t many coral reefs in Manatee Bay, but elsewhere in the Florida Keys, scientists diving at Cheeca Rocks found bleaching and even death in some of the Keys most resilient corals, said Ian Enochs, lead of the coral program at the National Oceanic and Atmospheric Administration Atlantic Oceanographic and Meteorological Laboratory.

NOAA researcher Andrew Ibarra, who took his kayak to the area because of the hot water, said, “I found that the entire reef was bleached out. Every single coral colony was exhibiting some form of paling, partial bleaching or full out bleaching.”Florida Keys’ most resilient reefs.

Some coral even had died, he said. This is on top of bleaching seen last week by the University of Miami as NOAA increased the level of alert for coral problems earlier this month.

Until the 1980s coral bleaching was mostly unheard of around the globe yet “now we’ve reached the point where it’s become routine,” Enochs said. Bleaching, which doesn’t kill coral but weakens it and could lead to death, occurs when water temperatures pass the upper 80s (low 30s Celsius), Enochs said.

“This is more, earlier than we have ever seen,” Enochs said. “I’m nervous by how early this is occurring.”

This all comes as sea surface temperatures worldwide have broken monthly records for heat in April, May and June, according to NOAA. And temperatures in the North Atlantic are off the charts — as much as 9 to 11 degrees (5 to 6 degrees Celsius) warmer than normal in some spots near Newfoundland, McNoldy said.