East Mississippi residents will have to deal with high temperatures until at least September.
The region and the central part of the state are under a heat advisory through Tuesday.
Anna Wolverton, a meteorologist with the National Weather Service in Jackson, said heat waves aren't uncommon in August, because it's considered to be the hottest month.
She attributed the hot weather to temperatures in the 90s combined with high humidity and dew points.
"Today and tomorrow, we're expecting heat indexes of 105 degrees to peak in the early to mid-afternoon," she said Monday. "That's what has caused the heat advisory."
After Tuesday, a front will move in, bringing a chance of rain and temperatures in the lower 90s. In the meantime, the NWS advises people not to go outside between the peak hours of 10 a.m. - 4 p.m. and to be aware of the signs of heat stress.
Wolverton encouraged people who work outside to stay in the shade and stay hydrated.
Forecasters are also warning of scorching heat across a wide stretch of the U.S. South and Midwest, where the heat index will feel as high as 117 degrees in some spots, according to the Associated Press.
Parts of 13 states on Monday were under heat advisories, from Texas, Louisiana and Florida in the South to Missouri and Illinois in the Midwest, the National Weather Service reported.
Some of the most oppressive conditions Monday were in Louisiana, Arkansas, Mississippi and Oklahoma, forecasters said.
It will feel like 116 degrees in parts of eastern Oklahoma, near Tulsa, on Monday, forecasters said. And parts of Arkansas just west of Memphis, Tennessee, could see heat indexes Monday of around 117 degrees.
Heat exhaustion and heat stroke are among the main threats in those areas.
Wolverton said temperatures will still be the 90s for the rest of the month and could not rule out the possibility of having another heatwave before August is over.
"We really don't anticipate any heat advisories at least through Thursday," he said.
Wolverton said weather on the Gulf Coast will be hot, but an advisory is not expected. The state won't see temperatures in the 80s until maybe mid-September, she said.
The Associated Press contributed to this report.