This is an update to this post. An excessive heat warning is in effect in the Washington, D.C. area Saturday through the evening hours. A high pressure system is currently over the southeast US coast, which is allowing for a surge of warm and humid air to travel northward.
The warning includes Alexandria, Virginia and will last from 10 a.m. to 11 p.m. this evening, according to the National Weather Service.
Heat index values are expected to range from 110 to 115 degrees. The combination of hot temperatures and high humidity will create a dangerous situation in which heat illnesses are possible, prompting the excessive heat warning.
Prolonged exposure could lead to heat exhaustion or heat stroke. To avoid this, be sure to schedule frequent rest breaks in an air conditioned or shaded place, if you have to be outside.