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

A heat advisory is in place across the Northeast, from Maryland to Maine, where residents are bracing for temperatures 5 to 15 degrees above average. The heat index -- what the temperature feels like with humidity -- could reach 103 degrees in Philadelphia on Wednesday and Thursday.

The NWS Greenville-Spartanburg SC issued a heat advisory at 12:27 a.m. on Friday valid between 2 p.m. and 7 p.m. The advisory is for Mecklenburg, Cabarrus and Union counties.

Lehigh and Northampton counties, as well as neighboring Bucks and Berks counties, will be under a heat advisory from 10 a.m. until 8 p.m. In the Lehigh Valley, a high of 92 is expected, but forecasters said it will feel closer to 102.

Thursday: A slight chance of showers and thunderstorms, mainly between 4 and 5 p.m. Mostly cloudy, then gradually becoming sunny, with a high near 93. Heat index values as high as 102. West wind 5 to 10 mph. Chance of precipitation is 20%.

On Wednesday at 1:59 p.m. an updated heat advisory was released by the National Weather Service in effect until Thursday at 10 p.m. for Passaic, Hudson, Bergen, Essex and Union counties.

The advisory is in effect until 8 p.m. Seek cool shelter: Opt for an air-conditioned room to stay comfortable. Avoid direct sun exposure: Protect yourself and check on vulnerable relatives and neighbors.