The heat is definitely on. 

Weather forecasters say some 40 states will experience temperatures in the 90s and above in the coming days.  The Midwest has been experiencing a heatwave that shows no signs of ending.  The National Weather Service says heat advisories and warnings were issued in 17 states in the central U.S. Sunday.

In Oklahoma City, the mercury Sunday topped 100 degrees for the 27th day this year.  Cooling centers are open in Detroit, Chicago and New York to help residents battle the heat. 

In Murfreesboro, the high today will be in the mid 90’s, so a little cooler then it was just two weeks ago when the heat index hit 110 degrees.

Medical experts say summer heat can be a killer.  Dr. Rahul Khare says high temperatures can cause heatstroke, which occurs when a person’s body can no longer maintain a normal temperature.

Meanwhile, Tropical Storm Bret is now churning in the Atlantic, northwest of The Bahamas.  Weather forecasters say Bret will gain strength in the coming days but the storm isn't expected to approach the U.S. coastline.