* WHAT...Dangerously hot conditions with heat index values as high as 117 degrees. * WHERE...Columbia, Dane, Green, Iowa, Lafayette, Rock, and Sauk Counties. * WHEN...Until 9 PM CDT this evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.