 WFMD News. The National Weather Service's heat advisory remains in effect until 8 o'clock tonight with heat index values of up to 109 degrees. And the impacts could be hot temperatures and high humidity, and that can cause some heat illnesses to occur. The Weather Service reminds people to drink plenty of fluids, stay in an air-conditioned room, 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.