Frost Dates for 17225 — Greencastle, Pennsylvania

Half of springs at Hagerstown Washington Co Airport, MD see their last 32°F night by April 7; only one in ten is past it by March 25, and one in ten still has one after April 21. Planting tender crops after April 12 leaves a 30% risk of a frost on them, after April 16 20%, and after April 21 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 86% of the 176 Pennsylvania 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 17 one year in ten. A hard freeze of 28°F follows 10 days later, around November 14; in spring the one-in-ten date for 28°F is April 8, 13 days before the 32°F one. The freeze-free season lasts 209 days in a typical year, longer than at 95% of the 176 Pennsylvania stations; it reaches 228 days one year in ten and falls short of 189 one year in ten. On average 93 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 19, and return around October 23. Severe cold of 16°F or below comes every winter, usually between December 28 and February 27.

July is the warmest month at Hagerstown Washington Co Airport, MD, averaging 87°F by day and 68°F at night; January is the coldest at 41°F and 25°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 3,893 growing degree days a year (base 50°F), more than at 98% of the 176 Pennsylvania stations. 36% of them (1,403) have built up by the end of June, and July adds the most, 856. Precipitation totals 35.6 inches a year, most in September (3.8") and least in February (2.0"); May to September bring 47% of it.

The nearest other station, Hagerstown 1 E, MD, 11 miles south of Greencastle and 166 feet lower, has a last frost 4 days later (April 11), a first frost 7 days earlier (October 28), a season 10 days shorter.

The first measurable snow (0.1 inch or more) in Greencastle usually arrives around December 9, and the last of the season around March 14. Those are the middle dates across the winters of 1991–2020 at Hagerstown 1 E, MD, 10.8 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 24 days after the last snow.

ZIP 17225 is 6 miles from Hagerstown Washington Co Airport, MD, which stands at 698 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 17225 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.