Frost Dates for 17222 — Fayetteville, Pennsylvania

Half of springs at S Mountain, PA see their last 32°F night by April 27; only one in ten is past it by April 13, and one in ten still has one after May 14. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 7 20%, and after May 14 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 6 one year in ten, and holds off past November 2 one year in ten. A hard freeze of 28°F follows 12 days later, around November 1; in spring the one-in-ten date for 28°F is May 1, 13 days before the 32°F one. The freeze-free season lasts 177 days in a typical year, longer than at 56% of the 176 Pennsylvania stations; it reaches 196 days one year in ten and falls short of 155 one year in ten. On average 129 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 10 days longer, to about May 7, and return around October 8. Severe cold of 16°F or below comes every winter, usually between December 8 and March 12.

July is the warmest month at S Mountain, PA, averaging 81°F by day and 62°F at night; January is the coldest at 36°F and 21°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 39% of years.

Warmth for growing adds up to 2,756 growing degree days a year (base 50°F), fewer than at 64% of the 176 Pennsylvania stations. 34% of them (929) have built up by the end of June, and July adds the most, 656. Precipitation totals 48.6 inches a year, most in September (5.1") and least in February (2.9"); May to September bring 46% of it.

The nearest other station, Chambersburg 1 ESE, PA, 7 miles northwest of Fayetteville and 880 feet lower, has a last frost 9 days earlier (April 18), a first frost 5 days later (October 25), a season 11 days longer.

The first measurable snow (0.1 inch or more) in Fayetteville usually arrives around December 10, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at S Mountain, PA, 3.3 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 17222 is 3 miles from S Mountain, PA, which stands at 1,520 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 17268 (Waynesboro). The 2023 USDA Plant Hardiness Zone Map lists ZIP 17222 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.