Frost Dates for 17094 — Thompsontown, Pennsylvania

Half of springs at Lewistown, PA see their last 32°F night by April 21; only one in ten is past it by April 6, and one in ten still has one after May 9. Planting tender crops after April 28 leaves a 30% risk of a frost on them, after May 1 20%, and after May 9 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 24 in half of years, as early as October 7 one year in ten, and holds off past November 7 one year in ten. A hard freeze of 28°F follows 12 days later, around November 5; in spring the one-in-ten date for 28°F is April 21, 18 days before the 32°F one. The freeze-free season lasts 185 days in a typical year, longer than at 69% of the 176 Pennsylvania stations; it reaches 206 days one year in ten and falls short of 162 one year in ten. On average 122 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 11 days longer, to about May 2, and return around October 13. Severe cold of 16°F or below comes every winter, usually between December 21 and March 3.

July is the warmest month at Lewistown, PA, averaging 85°F by day and 63°F at night; January is the coldest at 37°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 22% of years.

Warmth for growing adds up to 3,165 growing degree days a year (base 50°F), more than at 66% of the 176 Pennsylvania stations. 34% of them (1,073) have built up by the end of June, and July adds the most, 742. Precipitation totals 42.3 inches a year, most in September (4.4") and least in February (2.3"); May to September bring 47% of it.

The nearest other station, Bloserville 1 N, PA, 23 miles south of Thompsontown and 240 feet higher, has a last frost 3 days earlier (April 18), a first frost 2 days later (October 26), a season 6 days longer.

The first measurable snow (0.1 inch or more) in Thompsontown usually arrives around December 12, and the last of the season around March 14. Those are the middle dates across the winters of 1991–2020 at Lewistown, PA, 17.6 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 38 days after the last snow.

ZIP 17094 is 18 miles from Lewistown, PA, which stands at 460 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station; its figures are presented in full for 17044 (Lewistown). The 2023 USDA Plant Hardiness Zone Map lists ZIP 17094 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.