Baltimore, MD 21220 Frost Dates
21220, near Baltimore, MD: the frost window
Typically, the last spring freeze lands around 03/24, roughly 208 days out. Fall's first freeze usually shows up around 11/21, roughly 244 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Baltimore 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
Baltimore's growing season runs out in roughly 12 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 03/24 isn't a guarantee
03/24 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/08 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/04 and only about 1 year in 10 sees frost after that.
Baltimore against the rest of the dataset
Baltimore's growing season runs about 244 days, ranking 8,157 of 40,283 US ZIP codes measured here, longest to shortest. Within MD, it ranks 26 of 583.
Learn more
Two guides worth reading on 21220: local microclimates, on what one yard in Baltimore can differ from the 21220 normal, and zone vs. frost date, on why Zone 8a and Baltimore's frost date answer different questions.