The mercury hit 95 degrees in D.C. Monday afternoon as the region sweltered, tying a record high at Reagan National Airport set in 2002.
Storm Team4 declared both Monday and Tuesday Weather Alert Days.
D.C. officials are urging residents to take precautions due to the heat.
With temperatures expected to remain high throughout the week, officials are encouraging residents to stay indoors as much as possible, turn on their air conditioners or fans and drink water to stay hydrated.
Officials recommended wearing lightweight, loose-fitting clothing and applying sunscreen 20 minutes before going outside. Officials warned residents not to leave children or pets in vehicles.
In addition, a "Code Orange" air quality alert was in effect Monday for the D.C. metro area. The alert means air pollution may be unhealthy for children, people suffering from asthma, heart disease or lung diseases, and senior citizens. Those groups of people should avoid strenuous activity or outdoor exercise, officials said.
Tuesday may feel even hotter, with the "feels like" temperature reaching 100 degrees or more.
Humidity will rise Wednesday, with some late-day showers and storms possible as a backdoor cold front moves through the region.
Storm Team4 meteorologist Amelia Draper said while the threat for severe weather Wednesday isn't huge, storms could be slow-moving with heavy rainfall, leading to some areas of flash flooding.
Some relief from the heat is expected Thursday, with temperatures cooling off toward the end of the week.