Forget about any worries of tropical weather today. Instead pay attention to the heat: temperatures in Jacksonville could feel as high as 113 degrees.

The heat index could get as high as 111 in South Florida, with the strongest heat expected along the southern Gulf Coast. Temperatures are expected to climb into the mid 90s over inland areas, with heat indices ranging between 100 and 107 in Southwest Florida.

On Friday, 17 million people are under flood alerts across the Gulf Coast and in the mid-Atlantic, and 19 million are under heat alerts across the mid-Atlantic, southern Florida and Mississippi Valley.

A heat advisory was issued for South Florida from 10 a.m. to 7 p.m. Thursday as the heat index could be as high as 100 degrees. Weather forecast: Heat advisory issued for Miami, Broward | Miami Herald

Heat advisories don’t usually come this late in the year, even in steamy South Florida. “It is unusual,” agreed Ana Torres-Vazquez, a meteorologist for the National Weather Service in Miami.

In Florida, except for Miami-Dade County, the National Weather Services offices around the state would issue a heat advisory if the heat index is expected to reach 108 to 112 degrees. The National ...