Frost Dates for 20735 — Clinton, Maryland

Half of springs at Oxon Hill, MD see their last 32°F night by April 3; only one in ten is past it by March 19, and one in ten still has one after April 15. Planting tender crops after April 7 leaves a 30% risk of a frost on them, after April 10 20%, and after April 15 10%. The 12 days between the even-odds date and the one-in-ten date is narrower than at 90% of the 50 Maryland stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 8 in half of years, as early as October 24 one year in ten, and holds off past November 23 one year in ten. A hard freeze of 28°F follows 11 days later, around November 19; in spring the one-in-ten date for 28°F is April 3, 12 days before the 32°F one. The freeze-free season lasts 217 days in a typical year, longer than at 64% of the 50 Maryland stations; it reaches 240 days one year in ten and falls short of 200 one year in ten. On average 80 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 15, and return around October 27. Severe cold of 16°F or below comes in 93% of winters, usually between January 4 and February 12.

July is the warmest month at Oxon Hill, MD, averaging 88°F by day and 69°F at night; January is the coldest at 44°F and 27°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 60% of years.

Warmth for growing adds up to 4,190 growing degree days a year (base 50°F), more than at 72% of the 50 Maryland stations. 36% of them (1,507) have built up by the end of June, and July adds the most, 880. Precipitation totals 47.1 inches a year, most in July (5.0") and least in February (2.9"); May to September bring 49% of it.

The nearest other station, Washington Reagan Airport, VA, 10 miles northwest of Clinton and 180 feet lower, has a last frost 10 days earlier (March 24), a first frost 10 days later (November 18), a season 24 days longer.

The first measurable snow (0.1 inch or more) in Clinton usually arrives around December 8, and the last of the season around March 18. Those are the middle dates across the winters of 1991–2020 at Oxon Hill, MD, 5.9 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 16 days after the last snow.

ZIP 20735 is 6 miles from Oxon Hill, MD, which stands at 190 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 17 other ZIP codes share the station; its figures are presented in full for 20744 (Fort Washington). The 2023 USDA Plant Hardiness Zone Map lists ZIP 20735 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.