Forecasters said temperatures could climb to 100 degrees for some locations in the Upstate on Tuesday.
The National Weather Service issued a heat advisory for nearly all of the Upstate and northeast Georgia, and Polk, McDowell and Rutherford counties in North Carolina. The advisory is in effect from 11 a.m. to 9 p.m.
Forecasters said high temperatures will climb into the upper 90s to near 100 degrees for some areas. They said the high heat combined with high humidity will make it feel like between 105 and 109 degrees.
The weather service said people who work or spend time outside should take extra precautions to avoid heat-related illness. It said workers should schedule frequent breaks in a shaded or air-conditioned areas.
Experts said people who will be outside should drink plenty of non-alcoholic, non-caffeinated beverages and wear light-weight and light-colored clothing.
FOX Carolina meteorologist Alexandra Wilson said isolated thunderstorms were also forecast for Tuesday, which could bring some brief relief for some.
Wilson said temperatures will return to near-average levels by Thursday.
Greenville football player collapses during practice
A player on the Greenville High School football team collapsed Monday morning, and the school district wants to remind athletes the importance of drinking water when the temperatures are hot and the air is humid.
The athletic department said the training staff jumped right in to revive the young man, using an ice bath and calling an ambulance for intravenous treatments, and the player quickly felt better.
Bill Utsey, athletic director for Greenville County schools, said the training staff determines if it is too hot for athletes to practice or train outdoors, and Monday morning was not close to being called extreme heat.