DC heat dome: Extreme Heat Warning in effect Friday and Saturday for Fourth of July

An Extreme Heat Warning is in effect across the Washington, D.C., region Friday and Saturday for the Fourth of July holiday weekend, keeping dangerously hot conditions in place as heat index values climb well into the triple digits. The National Weather Service has issued an Extreme Heat Warning from 10 a.m. to 9 p.m. Friday, with a second warning in effect from 10 a.m. to 9 p.m. Saturday. The alerts cover Washington, D.C., along with portions of central, north‑central, northeast, northern and southern Maryland, and central, northern and northwest Virginia. Officials say heat index values between 110 and 113 degrees are expected each afternoon, creating life‑threatening conditions. Heat‑related illnesses increase significantly during periods of extreme heat and high humidity, according to the Weather Service. Residents and visitors are urged to drink plenty of fluids, stay in air‑conditioned spaces, avoid direct sun and check on relatives and neighbors. Young children and pets should never be left in unattended vehicles, where interior temperatures can become lethal within minutes. Officials advise wearing lightweight, loose‑fitting clothing and limiting strenuous outdoor activity to early morning or evening hours. They say people should take action immediately if they notice symptoms of heat exhaustion or heat stroke.