The extreme heat is taxing local power grids.
People in the region are cranking up the air conditioning, and that is translating into scattered power outages.
In Ballston, an underground transformer blew overnight, knocking out electricity and shutting down a section of Wilson Boulevard.
Residents are being asked to conserve electricity for the next several days.
A heat warning remains in effect until 10 p.m. and air quality is in the unhealthy "red" range. People with health and respiratory problems are warned to stay indoors. Even the healthy are advised to limit outdoor activity during the hottest time of the day.