Frost Dates for 20733 — Churchton, Maryland

Half of springs at Annapolis Naf, MD see their last 32°F night by March 23; only one in ten is past it by March 8, and one in ten still has one after April 6. Planting tender crops after March 31 leaves a 30% risk of a frost on them, after April 2 20%, and after April 6 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 20 in half of years, as early as November 4 one year in ten, and holds off past December 5 one year in ten. A hard freeze of 28°F follows 13 days later, around December 3; in spring the one-in-ten date for 28°F is March 28, 9 days before the 32°F one. The freeze-free season lasts 241 days in a typical year, longer than at 96% of the 50 Maryland stations; it reaches 265 days one year in ten and falls short of 219 one year in ten. On average 56 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 13 days longer, to about April 5, and return around November 6. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 79%.

July is the warmest month at Annapolis Naf, MD, averaging 86°F by day and 72°F at night; January is the coldest at 43°F and 30°F. A freezing night is all but certain in every month from December to March (a 90% chance or more). From May to October the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 26% of years.

Warmth for growing adds up to 4,246 growing degree days a year (base 50°F), more than at 76% of the 50 Maryland stations. 35% of them (1,475) have built up by the end of June, and July adds the most, 897.

The nearest other station, Annapolis Police Brks, MD, 13 miles north of Churchton, has a last frost 4 days later (March 27), a first frost 7 days earlier (November 13), a season 7 days shorter.

The first measurable snow (0.1 inch or more) in Churchton usually arrives around December 20, and the last of the season around February 18. Those are the middle dates across the winters of 1991–2020 at Upper Marlboro 3 NNW, MD, 13.6 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 33 days after the last snow.

ZIP 20733 is 13 miles from Annapolis Naf, MD, which stands at 8 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 21403 (Annapolis). The 2023 USDA Plant Hardiness Zone Map lists ZIP 20733 in zone 8a, the band where the coldest night of the year averaged 10 to 15°F (-12.2 to -9.4°C) over 1991–2020; a zone describes winter lows, not frost dates.