Washington, DC 20507 Frost Dates
20507, near Washington, DC: the frost window
The last spring frost here typically falls around 03/29, about 213 days from today. Fall's first freeze usually shows up around 11/08, roughly 224 days after the last spring frost.
Zone 8a (10 to 15°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Washington, not a forecast for this year.
Stretching the season past the first frost
Washington's growing season runs out in roughly 10 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 03/29 isn't a guarantee
03/29 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/15 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/11 and only about 1 year in 10 sees frost after that.
Washington against the rest of the dataset
Washington's growing season runs about 224 days, ranking 11,672 of 40,283 US ZIP codes measured here, longest to shortest. Within DC, it ranks 200 of 246.
Learn more
Two guides worth reading on 20507: zone vs. frost date, on why Zone 8a and Washington's frost date answer different questions, and the frost range, on how to read the range around Washington's dates instead of trusting one.