* WHAT...Heat index values up to 100 expected.
* WHERE...In Maryland, Eastern Garrett and Western Garrett Counties. In Virginia, Central Virginia Blue Ridge, Northern Virginia Blue Ridge, and Western Highland Counties. In West Virginia, Western Grant and Western Pendleton Counties.
* WHEN...Until 8 PM EDT this evening.
* IMPACTS...Hot temperatures and high humidity may cause heat illnesses.
* ADDITIONAL DETAILS...Early morning low temperatures around 70 combined with oppressive humidity will result in little to no overnight relief. Prolonged excessive heat may impact power, water, and transportation systems.