Frost Dates for 17320 — Fairfield, Pennsylvania

Half of springs at Emmitsburg 2 SE, MD see their last 32°F night by April 22; only one in ten is past it by April 7, and one in ten still has one after May 9. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 4 20%, and after May 9 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 50% of the 176 Pennsylvania stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 20 in half of years, as early as October 7 one year in ten, and holds off past November 2 one year in ten. A hard freeze of 28°F follows 11 days later, around October 31; in spring the one-in-ten date for 28°F is April 25, 14 days before the 32°F one. The freeze-free season lasts 179 days in a typical year, longer than at 63% of the 176 Pennsylvania stations; it reaches 200 days one year in ten and falls short of 158 one year in ten. On average 114 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 May 4, and return around October 10. Severe cold of 16°F or below comes every winter, usually between December 12 and March 6.

July is the warmest month at Emmitsburg 2 SE, MD, averaging 85°F by day and 64°F at night; January is the coldest at 40°F and 22°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 28% of years.

Warmth for growing adds up to 3,329 growing degree days a year (base 50°F), more than at 81% of the 176 Pennsylvania stations. 34% of them (1,131) have built up by the end of June, and July adds the most, 770. Precipitation totals 46.8 inches a year, most in September (5.2") and least in February (2.6"); May to September bring 46% of it.

The nearest other station, Eisenhower Nhs, PA, 8 miles east of Fairfield, has a last frost 2 days later (April 24), a first frost 1 day later (October 21), a season 1 day longer.

The first measurable snow (0.1 inch or more) in Fairfield usually arrives around December 10, and the last of the season around March 18. Those are the middle dates across the winters of 1991–2020 at Emmitsburg 2 SE, MD, 7.6 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 35 days after the last snow.

ZIP 17320 is 8 miles from Emmitsburg 2 SE, MD, which stands at 403 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 21787 (Taneytown). The 2023 USDA Plant Hardiness Zone Map lists ZIP 17320 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.