Frost Dates for 15563 — Stoystown, Pennsylvania

Half of springs at Laurel Summit, PA see their last 32°F night by May 6; only one in ten is past it by April 22, and one in ten still has one after May 23. Planting tender crops after May 13 leaves a 30% risk of a frost on them, after May 18 20%, and after May 23 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 12 in half of years, as early as October 1 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 12 days later, around October 24; in spring the one-in-ten date for 28°F is May 15, 8 days before the 32°F one. The freeze-free season lasts 159 days in a typical year, shorter than at 76% of the 176 Pennsylvania stations; it reaches 180 days one year in ten and falls short of 137 one year in ten. On average 146 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 16, and return around October 3. Severe cold of 16°F or below comes every winter, usually between November 24 and March 28.

July is the warmest month at Laurel Summit, PA, averaging 75°F by day and 58°F at night; January is the coldest at 31°F and 14°F. A freezing night is all but certain in every month from October 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 67% of years.

Warmth for growing adds up to 2,036 growing degree days a year (base 50°F), fewer than at 96% of the 176 Pennsylvania stations. 32% of them (650) have built up by the end of June, and July adds the most, 507. Precipitation totals 56.5 inches a year, most in June (5.9") and least in February (3.5"); May to September bring 46% of it.

The nearest other station, Laurel Mountain, PA, 14 miles northwest of Stoystown, has a last frost 10 days earlier (April 26), a first frost 5 days later (October 17), a season 13 days longer.

The first measurable snow (0.1 inch or more) in Stoystown usually arrives around November 21, and the last of the season around March 30. Those are the middle dates across the winters of 1991–2020 at Boswell, PA, 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 37 days after the last snow.

ZIP 15563 is 11 miles from Laurel Summit, PA, which stands at 2,730 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 15531 (Boswell). The 2023 USDA Plant Hardiness Zone Map lists ZIP 15563 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.