Frost Dates for 21631 — East New Market, Maryland

Half of springs at Vienna, MD see their last 32°F night by April 8; only one in ten is past it by March 24, and one in ten still has one after April 23. Planting tender crops after April 15 leaves a 30% risk of a frost on them, after April 19 20%, and after April 23 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 52% of the 50 Maryland stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 4 in half of years, as early as October 22 one year in ten, and holds off past November 20 one year in ten. A hard freeze of 28°F follows 13 days later, around November 17; in spring the one-in-ten date for 28°F is April 12, 11 days before the 32°F one. The freeze-free season lasts 209 days in a typical year, longer than at 58% of the 50 Maryland stations; it reaches 231 days one year in ten and falls short of 188 one year in ten. On average 83 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 21, and return around October 23. Severe cold of 16°F or below comes in 96% of winters, usually between January 2 and February 15.

July is the warmest month at Vienna, MD, averaging 90°F by day and 69°F at night; January is the coldest at 48°F and 28°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 74% of years.

Warmth for growing adds up to 4,375 growing degree days a year (base 50°F), more than at 84% of the 50 Maryland stations. 35% of them (1,537) have built up by the end of June, and July adds the most, 911.

The nearest other station, Royal Oak 2 SSW, MD, 16 miles northwest of East New Market, has a last frost 7 days earlier (April 1), a first frost 3 days later (November 7), a season 11 days longer.

The first measurable snow (0.1 inch or more) in East New Market usually arrives around December 28, and the last of the season around March 2. Those are the middle dates across the winters of 1991–2020 at Royal Oak 2 SSW, MD, 16 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 37 days after the last snow.

ZIP 21631 is 10 miles from Vienna, MD, which stands at 10 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 21643 (Hurlock). The 2023 USDA Plant Hardiness Zone Map lists ZIP 21631 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.