Bel Air, MD 21009 Frost Dates
21009, near Bel Air, MD: the frost window
Typically, the last spring freeze lands around 04/10, roughly 225 days out. Fall's first freeze usually shows up around 10/30, roughly 201 days after the last spring frost.
Bel Air sits in USDA Zone 7b (5 to 10°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Bel Air's growing season runs out in roughly 9 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/10 isn't a guarantee
04/10 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/27 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/30 and only about 1 year in 10 sees frost after that.
Bel Air against the rest of the dataset
At roughly 201 frost-free days, Bel Air places 17,474 of 40,283 ZIP codes in this dataset. Within MD, it ranks 447 of 583.
Learn more
Two guides worth reading on 21009: local microclimates, on what one yard in Bel Air can differ from the 21009 normal, and zone vs. frost date, on why Zone 7b and Bel Air's frost date answer different questions.