Frost Dates for 21114 — Crofton, Maryland

Half of springs at Glenn Dale Bell Stn, MD see their last 32°F night by April 22; only one in ten is past it by April 3, and one in ten still has one after May 9. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 3 20%, and after May 9 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 64% of the 50 Maryland stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 22 in half of years, as early as October 7 one year in ten, and holds off past November 6 one year in ten. A hard freeze of 28°F follows 10 days later, around November 1; in spring the one-in-ten date for 28°F is April 30, 9 days before the 32°F one. The freeze-free season lasts 183 days in a typical year, shorter than at 76% of the 50 Maryland stations; it reaches 205 days one year in ten and falls short of 161 one year in ten. On average 112 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 11 days longer, to about May 3, and return around October 12. Severe cold of 16°F or below comes every winter, usually between December 11 and March 1.

July is the warmest month at Glenn Dale Bell Stn, MD, averaging 89°F by day and 66°F at night; January is the coldest at 44°F and 22°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 25% of years.

Warmth for growing adds up to 3,762 growing degree days a year (base 50°F), fewer than at 60% of the 50 Maryland stations. 34% of them (1,278) have built up by the end of June, and July adds the most, 846.

The nearest other station, Annapolis Police Brks, MD, 10 miles east of Crofton, has a last frost 26 days earlier (March 27), a first frost 22 days later (November 13), a season 51 days longer.

The first measurable snow (0.1 inch or more) in Crofton usually arrives around December 11, and the last of the season around March 11. Those are the middle dates across the winters of 1991–2020 at Baltimore Wash International Airport, MD, 10.7 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 42 days after the last snow.

ZIP 21114 is 7 miles from Glenn Dale Bell Stn, MD, which stands at 150 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 8 other ZIP codes share the station; its figures are presented in full for 20706 (Lanham). The 2023 USDA Plant Hardiness Zone Map lists ZIP 21114 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.