Gaithersburg, MD 20847 Frost Dates
20847, near Gaithersburg, MD: the frost window
Typically, the last spring freeze lands around 04/01, roughly 216 days out. Fall's first freeze usually shows up around 11/06, roughly 219 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Gaithersburg in Zone 7b (5 to 10°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
Gaithersburg'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.
The actual range around Gaithersburg's last frost
04/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/19 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/15 and only about 1 year in 10 sees frost after that.
Gaithersburg against the rest of the dataset
At roughly 219 frost-free days, Gaithersburg places 12,928 of 40,283 ZIP codes in this dataset. Within MD, it ranks 201 of 583.
Learn more
Two guides worth reading on 20847: zone vs. frost date, on why Zone 7b and Gaithersburg's frost date answer different questions, and the frost range, on how to read the range around Gaithersburg's dates instead of trusting one.