* WHAT...Heat index values up to 105.
* WHERE...Portions of south central, southwest, and west central Illinois and central, east central, northeast, and southeast Missouri.
* WHEN...For the Extreme Heat Warning, until 10 PM CDT this evening. For the Heat Advisory, from 10 PM this evening to 8 PM CDT Saturday.
* IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events. Hot temperatures and high humidity may cause heat illnesses.