A high pressure system is currently over the southeast US coast, allowing for a surge of warm and humid air to travel northward.
Therefore, the National Weather Service has issued a Heat Advisory through 8:00 PM tonight (Monday, June 18, 2018) for the Washington, D.C. area including Alexandria, Virginia. The combination of the heat and humidity will make it feel as high as 105 degrees.
A Heat Advisory has been issued for portions of the region from Noon – 8 PM today. pic.twitter.com/8w6Yg9NzHJ
— NWS DC/Baltimore (@NWS_BaltWash) June 18, 2018
Because of this, it will be terribly awful in the afternoon, when 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.