Frost Dates for 20905 — Silver Spring, Maryland

Half of springs at Laurel 3 W, MD see their last 32°F night by April 5; only one in ten is past it by March 21, and one in ten still has one after April 19. Planting tender crops after April 10 leaves a 30% risk of a frost on them, after April 14 20%, and after April 19 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 62% of the 50 Maryland stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 9 in half of years, as early as October 27 one year in ten, and holds off past November 24 one year in ten. A hard freeze of 28°F follows 12 days later, around November 21; in spring the one-in-ten date for 28°F is April 8, 11 days before the 32°F one. The freeze-free season lasts 218 days in a typical year, longer than at 72% of the 50 Maryland stations; it reaches 238 days one year in ten and falls short of 198 one year in ten. On average 86 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 12 days longer, to about April 17, and return around October 29. Severe cold of 16°F or below comes in 97% of winters, usually between January 5 and February 19.

July is the warmest month at Laurel 3 W, MD, averaging 89°F by day and 69°F at night; January is the coldest at 43°F and 26°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 64% of years.

Warmth for growing adds up to 4,262 growing degree days a year (base 50°F), more than at 78% of the 50 Maryland stations. 35% of them (1,501) have built up by the end of June, and July adds the most, 899. Precipitation totals 47.5 inches a year, most in September (4.7") and least in February (2.7"); May to September bring 45% of it.

The nearest other station, Beltsville, MD, 6 miles southeast of Silver Spring and 255 feet lower, has a last frost 5 days later (April 10), a first frost 8 days earlier (November 1), a season 16 days shorter.

The first measurable snow (0.1 inch or more) in Silver Spring usually arrives around December 14, and the last of the season around March 2. Those are the middle dates across the winters of 1991–2020 at Beltsville, MD, 6.1 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 34 days after the last snow.

ZIP 20905 is 5 miles from Laurel 3 W, MD, which stands at 400 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 21044 (Columbia). The 2023 USDA Plant Hardiness Zone Map lists ZIP 20905 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.