* WHAT...Dangerously hot conditions with peak heat index values 110 to locally over 115 degrees expected. * WHERE...Iroquois, Boone, Eastern Will, Kane, Kankakee, Kendall, McHenry, Northern Will, and Southern Will Counties. * WHEN...Until 9 PM CDT this evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events.