Frost Dates for 20872 — Damascus, Maryland

Half of springs at Damascus 3 SSW, MD see their last 32°F night by April 14; only one in ten is past it by March 31, and one in ten still has one after May 2. Planting tender crops after April 20 leaves a 30% risk of a frost on them, after April 25 20%, and after May 2 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 76% of the 50 Maryland stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 29 in half of years, as early as October 13 one year in ten, and holds off past November 12 one year in ten. A hard freeze of 28°F follows 10 days later, around November 8; in spring the one-in-ten date for 28°F is April 16, 16 days before the 32°F one. The freeze-free season lasts 196 days in a typical year, shorter than at 66% of the 50 Maryland stations; it reaches 216 days one year in ten and falls short of 174 one year in ten. On average 98 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 14 days longer, to about April 28, and return around October 17. Severe cold of 16°F or below comes every winter, usually between December 24 and March 3.

July is the warmest month at Damascus 3 SSW, MD, averaging 84°F by day and 66°F at night; January is the coldest at 39°F and 25°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 85% of years and May still brings one in 12% of years.

Warmth for growing adds up to 3,528 growing degree days a year (base 50°F), fewer than at 72% of the 50 Maryland stations. 35% of them (1,248) have built up by the end of June, and July adds the most, 780. Precipitation totals 48.0 inches a year, most in September (4.8") and least in February (3.0"); May to September bring 47% of it.

The nearest other station, Rockville 1 NE, MD, 13 miles south of Damascus and 260 feet lower, has a last frost 13 days earlier (April 1), a first frost 8 days later (November 6), a season 23 days longer.

The first measurable snow (0.1 inch or more) in Damascus usually arrives around December 6, and the last of the season around March 22. Those are the middle dates across the winters of 1991–2020 at Damascus 3 SSW, MD, 1.4 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 23 days after the last snow.

ZIP 20872 is 1 mile from Damascus 3 SSW, MD, which stands at 700 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 13 other ZIP codes share the station; its figures are presented in full for 20874 (Germantown). The 2023 USDA Plant Hardiness Zone Map lists ZIP 20872 in zone 7b, the band where the coldest night of the year averaged 5 to 10°F (-15.0 to -12.2°C) over 1991–2020; a zone describes winter lows, not frost dates.