As Washington D.C. and surrounding areas brace for scorching heat today, the National Weather Service has issued a Heat Advisory, warning residents of potentially dangerous conditions. With temperatures soaring and humidity gripping the air, the advisory remains in effect from 11 AM this morning until 8 PM EDT this evening. The heat index, a measure of how hot it feels when relative humidity is factored with the actual air temperature, could reach up to 106 degrees, according to the National Weather Service.