A heat advisory is in effect from 11:00 this morning until 8:00 tomorrow evening for Central Pennsylvania. Heat index values of up to 104 degrees are expected. The National Weather Service is warning individuals that hot temperatures and high humidity may cause heat illnesses. You are advised to drink plenty of water, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. This is especially true during hot weather when car interiors can reach lethal temperatures in a matter of minutes.