Washington, DC 20419 Frost Dates
20419, near Washington, DC: the frost window
Around 03/29 is the usual last spring frost, about 213 days away. Fall's first freeze usually shows up around 11/08, roughly 224 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Washington in Zone 8a (10 to 15°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
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
At roughly 224 frost-free days, Washington places 11,647 of 40,283 ZIP codes in this dataset. Within DC, it ranks 175 of 246.
Learn more
Two guides worth reading on 20419: local microclimates, on what one yard in Washington can differ from the 20419 normal, and zone vs. frost date, on why Zone 8a and Washington's frost date answer different questions.