MOUNT JACKSON, Va — A heat advisory is now in place for northern and eastern counties in the Shenandoah Valley.

According to the National Weather Service, temperatures in Shenandoah, Page, Frederick, Clarke and Warren counties are expected to reach at least the upper 90s – with a heat index reaching up to 105. While other parts of the listening area aren’t included in the advisory, this afternoon’s heat will certainly be dangerous.

For folks staying outside, federal officials advise keeping an eye out for symptoms of heat exhaustion. They say this could include muscle cramps, faintness or dizziness, and cool, pale or clammy skin.

Perspiration is expected – but if sweating stops and a throbbing headache develops, officials say that’s a sign of potentially deadly heat stroke.