Frost Dates for 19440 — Hatfield, Pennsylvania

Half of springs at Sellersville, PA see their last 32°F night by April 26; only one in ten is past it by April 12, and one in ten still has one after May 12. Planting tender crops after May 1 leaves a 30% risk of a frost on them, after May 6 20%, and after May 12 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 17 in half of years, as early as October 5 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 11 days later, around October 28; in spring the one-in-ten date for 28°F is April 30, 12 days before the 32°F one. The freeze-free season lasts 175 days in a typical year, shorter than at 48% of the 176 Pennsylvania stations; it reaches 195 days one year in ten and falls short of 156 one year in ten. On average 131 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 6, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 6 and March 10.

July is the warmest month at Sellersville, PA, averaging 85°F by day and 63°F at night; January is the coldest at 38°F and 19°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 33% of years.

Warmth for growing adds up to 3,059 growing degree days a year (base 50°F), more than at 56% of the 176 Pennsylvania stations. 33% of them (998) have built up by the end of June, and July adds the most, 742. Precipitation totals 51.7 inches a year, most in July (5.3") and least in February (3.1"); May to September bring 47% of it.

The nearest other station, Graterford 1 E, PA, 8 miles southwest of Hatfield, has a last frost 2 days earlier (April 24), a first frost 2 days earlier (October 15), a season 2 days shorter.

The first measurable snow (0.1 inch or more) in Hatfield usually arrives around December 17, and the last of the season around March 15. Those are the middle dates across the winters of 1991–2020 at Sellersville, PA, 5.4 miles away: half of years saw snow earlier, half later. Snow fell in 95% of those winters. The last 32°F night of spring typically comes 42 days after the last snow.

ZIP 19440 is 5 miles from Sellersville, PA, which stands at 302 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 9 other ZIP codes share the station; its figures are presented in full for 18951 (Quakertown). The 2023 USDA Plant Hardiness Zone Map lists ZIP 19440 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.