* WHAT...For the Heat Advisory, heat index values up to 103 expected. For the Extreme Heat Watch, dangerously hot conditions with heat index values up to 107 possible. * WHERE...Portions of southern Illinois, southwest Indiana, western Kentucky, and southeast Missouri. * WHEN...For the Heat Advisory, from 10 AM CDT /11 AM EDT/ Monday to 10 AM CDT /11 AM EDT/ Tuesday. For the Extreme Heat Watch, from Tuesday morning through Friday evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events. Hot temperatures and high humidity may cause heat illnesses.