Heat Wave Grips South, Midwest Region

July 16, 2011— -- A heat wave is gripping the south and the midwest of the country this weekend.

From Texas and Louisiana to the Canadian border, 13 states are under some type of heat alert, watch, warning and advisory according to weather forecasters.

In Chicago, temperatures are expected to hit the 90s today as the city kicks off the "Taste of River North."

"Our restaurant vendors - they sell water and soft drinks," Larry Janus of Taste of River North told Chicago ABC News affiliate WLS Friday. "We ask them - please make sure you're stocked up and it's cold."

With several days of extreme heat in the forecast, prolonged exposure could make matters worse according to Dr. Teresa Davis of Rush University Medical Center in Chicago.

"If there's multiple days in a row of your body being exposed to that type of heat it's harder for your body to recover especially the elderly," Davis said.

Forecaster Ben Deubelbeiss of The National Weather Service said things are expected to get even hotter next week in the Chicago area.

"Sunday we're expecting heat indexes right around a 100 degrees and probably a couple degrees warmer on Monday. A little bit of cool down on Tuesday as we get a weak cold front that pushes through the area but Wednesday and Thursday look to be the hottest days," Deubelbeiss said.

ABC News' Amber Sullins, Chris Bury and the Associated Press contributed to this report.