Frost Dates for 21773 — Myersville, Maryland

Half of springs at Catoctin Mountain Park, MD see their last 32°F night by April 14; only one in ten is past it by April 2, and one in ten still has one after April 30. Planting tender crops after April 21 leaves a 30% risk of a frost on them, after April 24 20%, and after April 30 10%. The 16 days between the even-odds date and the one-in-ten date is wider than at 50% of the 50 Maryland stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 30 in half of years, as early as October 14 one year in ten, and holds off past November 11 one year in ten. A hard freeze of 28°F follows 9 days later, around November 8; in spring the one-in-ten date for 28°F is April 17, 13 days before the 32°F one. The freeze-free season lasts 197 days in a typical year, shorter than at 64% of the 50 Maryland stations; it reaches 215 days one year in ten and falls short of 176 one year in ten. On average 106 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 27, and return around October 20. Severe cold of 16°F or below comes every winter, usually between December 18 and March 5.

July is the warmest month at Catoctin Mountain Park, MD, averaging 84°F by day and 65°F at night; January is the coldest at 39°F and 23°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month.

Warmth for growing adds up to 3,429 growing degree days a year (base 50°F), fewer than at 76% of the 50 Maryland stations. 36% of them (1,227) have built up by the end of June, and July adds the most, 749. Precipitation totals 48.6 inches a year, most in September (5.3") and least in February (3.0"); May to September bring 45% of it.

The nearest other station, Smithsburg 2NW, MD, 9 miles north of Myersville and 940 feet lower, has a last frost 11 days later (April 25), a first frost 11 days earlier (October 19), a season 21 days shorter.

The first measurable snow (0.1 inch or more) in Myersville usually arrives around December 17, and the last of the season around March 5. Those are the middle dates across the winters of 1991–2020 at Catoctin Mountain Park, MD, 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 40 days after the last snow.

ZIP 21773 is 9 miles from Catoctin Mountain Park, MD, which stands at 1,610 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 21788 (Thurmont). The 2023 USDA Plant Hardiness Zone Map lists ZIP 21773 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.