Gaithersburg, MD 20898 Frost Dates
20898, near Gaithersburg, MD: the frost window
The last spring frost here typically falls around 04/01, about 216 days from today. 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.
How much risk comes with planting early here
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
About 219 days separate Gaithersburg's last and first frost, putting it 12,942 of 40,283 ZIP codes nationally. Within MD, it ranks 215 of 583.
Learn more
Two guides worth reading on 20898: the frost range, on how to read the range around Gaithersburg's dates instead of trusting one, and local microclimates, on what one yard in Gaithersburg can differ from the 20898 normal.