* WHAT. A prolonged period of dangerously hot conditions with heat index values near 100 degrees. * WHERE. Portions of east central and southeast Indiana, northeast and northern Kentucky, and central, south central, southwest, and west central Ohio. * WHEN. Until 8 PM EDT Friday. * IMPACTS. The combination of excessive heat due to temperatures in the 90s and high humidity will increase the threat of heat illnesses.

* WHAT. A prolonged period of dangerously hot conditions with heat index values near 100 degrees. * WHERE. Portions of east central and southeast Indiana, northeast and northern Kentucky and central, south central, southwest and west central Ohio. * WHEN. Until 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. Heat index values ranging from 100 to 105 degrees during the day. * WHERE. Portions of east central Ohio, northwest, southwest, and western Pennsylvania, and northern and the northern panhandle of West Virginia. * WHEN. Until 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.

* WHAT. Heat index values up to 100. * WHERE. Portions of northeast Kentucky, southeast Ohio, and central, northern, southern, and western West Virginia. * WHEN. Until 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses. * ADDITIONAL DETAILS. Heat stress increases with the number of consecutive hot days. While heat indices may be slightly lower today, values will rise on Thursday and again on Friday.