Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.

* WHAT...For the Heat Advisory, heat index values up to 104 expected. For the Extreme Heat Watch, dangerously hot conditions with heat index values up to 109 possible. * WHERE...In Maryland, Washington County. In Virginia, Clarke, Frederick, Page, Shenandoah, and Warren Counties. In West Virginia, Berkeley and Jefferson Counties. * WHEN...For the Heat Advisory, from noon today to 8 PM EDT this evening. For the Extreme Heat Watch, from Monday morning through Monday evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events. Hot temperatures and high humidity may cause heat illnesses.