Frost Dates for 19465 — Pottstown, Pennsylvania

Half of springs at Pottstown Limerick Airport, PA see their last 32°F night by April 20; only one in ten is past it by April 5, and one in ten still has one after May 6. Planting tender crops after April 27 leaves a 30% risk of a frost on them, after May 1 20%, and after May 6 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 23 in half of years, as early as October 9 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 11 days later, around November 3; in spring the one-in-ten date for 28°F is April 21, 15 days before the 32°F one. The freeze-free season lasts 186 days in a typical year, longer than at 72% of the 176 Pennsylvania stations; it reaches 207 days one year in ten and falls short of 164 one year in ten. On average 111 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 2, and return around October 12. Severe cold of 16°F or below comes every winter, usually between December 15 and March 3.

July is the warmest month at Pottstown Limerick Airport, PA, averaging 84°F by day and 64°F at night; January is the coldest at 37°F and 22°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 3,108 growing degree days a year (base 50°F), more than at 61% of the 176 Pennsylvania stations. 34% of them (1,047) have built up by the end of June, and July adds the most, 744. Precipitation totals 45.3 inches a year, most in September (4.8") and least in February (2.6"); May to September bring 47% of it.

The nearest other station, Glenmoore, PA, 9 miles southwest of Pottstown and 209 feet higher, has a last frost 9 days earlier (April 11), a first frost 9 days later (November 1), a season 19 days longer.

The first measurable snow (0.1 inch or more) in Pottstown usually arrives around December 6, and the last of the season around March 24. Those are the middle dates across the winters of 1991–2020 at Glenmoore, PA, 9 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 27 days after the last snow.

ZIP 19465 is 6 miles from Pottstown Limerick Airport, PA, which stands at 291 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 19464 (Pottstown). The 2023 USDA Plant Hardiness Zone Map lists ZIP 19465 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.