Frost Dates for 16001 — Butler, Pennsylvania

Half of springs at Butler 2 SW, 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 23. Planting tender crops after May 14 leaves a 30% risk of a frost on them, after May 19 20%, and after May 23 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 51% 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 14, 9 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 179 days one year in ten and falls short of 139 one year in ten. On average 140 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 19, and return around October 3. Severe cold of 16°F or below comes every winter, usually between December 1 and March 18.

July is the warmest month at Butler 2 SW, PA, averaging 82°F by day and 58°F at night; January is the coldest at 34°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 67% of years.

Warmth for growing adds up to 2,533 growing degree days a year (base 50°F), fewer than at 77% of the 176 Pennsylvania stations. 33% of them (839) have built up by the end of June, and July adds the most, 618. Precipitation totals 43.3 inches a year, most in June (4.3") and least in February (2.7"); May to September bring 47% of it.

The nearest other station, Slippery Rock 1 SSW, PA, 15 miles northwest of Butler and 260 feet higher, has the same 50% last-frost date, the same first-frost date, a season 1 day shorter.

The first measurable snow (0.1 inch or more) in Butler usually arrives around November 28, and the last of the season around March 27. Those are the middle dates across the winters of 1991–2020 at Butler 2 SW, PA, 2.5 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 41 days after the last snow.

ZIP 16001 is 3 miles from Butler 2 SW, PA, which stands at 1,000 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 8 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 16001 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.