Frost Dates for 16038 — Harrisville, Pennsylvania

Half of springs at Slippery Rock 1 SSW, PA see their last 32°F night by May 7; only one in ten is past it by April 22, and one in ten still has one after May 25. Planting tender crops after May 15 leaves a 30% risk of a frost on them, after May 19 20%, and after May 25 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 70% of the 176 Pennsylvania stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 14 in half of years, as early as October 1 one year in ten, and holds off past October 30 one year in ten. A hard freeze of 28°F follows 13 days later, around October 27; in spring the one-in-ten date for 28°F is May 15, 10 days before the 32°F one. The freeze-free season lasts 158 days in a typical year, shorter than at 77% of the 176 Pennsylvania stations; it reaches 180 days one year in ten and falls short of 136 one year in ten. On average 142 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 May 20, and return around October 1. Severe cold of 16°F or below comes every winter, usually between December 1 and March 20.

July is the warmest month at Slippery Rock 1 SSW, PA, averaging 81°F by day and 58°F at night; January is the coldest at 33°F and 17°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 66% of years.

Warmth for growing adds up to 2,473 growing degree days a year (base 50°F), fewer than at 80% of the 176 Pennsylvania stations. 33% of them (805) have built up by the end of June, and July adds the most, 609. Precipitation totals 45.3 inches a year, most in June (4.8") and least in February (2.7"); May to September bring 48% of it.

The nearest other station, Mercer, PA, 15 miles west of Harrisville, has a last frost 8 days later (May 15), a first frost 11 days earlier (October 3), a season 18 days shorter.

The first measurable snow (0.1 inch or more) in Harrisville usually arrives around November 19, and the last of the season around April 3. Those are the middle dates across the winters of 1991–2020 at Mercer, PA, 15 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 34 days after the last snow.

ZIP 16038 is 8 miles from Slippery Rock 1 SSW, PA, which stands at 1,260 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 16127 (Grove City). The 2023 USDA Plant Hardiness Zone Map lists ZIP 16038 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.