Temperatures soared to 99 degrees by Sunday afternoon throughout the D.C. area, with a heat index as high as 106 in some places.
D.C. and surrounding counties in Maryland and Virginia were under a heat advisory until 8 p.m. Sunday.
Stifling humidity added to Sunday's already intense heat. More dangerous heat is expected Monday and the heat index could reach as high as 110.
Storm Team4's Somara Theodore says to be sure to stay hydrated and limit any time spent outside.
D.C.'s COVID-19 testing sites will be closed Monday because of the heat. All meal distribution sites will remain open.
The National Parks Service said the Billy Goat Trail A in C&O Canal Park near Great Falls will be closed again Monday due to the heat.
Tuesday will be partly sunny, muggy and dangerously hot again with a heat index of 102-107°.
Remember to bring pets inside and check on your neighbors during the heatwave.
Some isolated storms are possible Monday and Tuesday.
Stay with Storm Team4 for the latest weather forecast.