Frost Dates for 19426 — Collegeville, Pennsylvania

Half of springs at Graterford 1 E, PA see their last 32°F night by April 24; only one in ten is past it by April 10, and one in ten still has one after May 9. Planting tender crops after May 1 leaves a 30% risk of a frost on them, after May 4 20%, and after May 9 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 72% of the 176 Pennsylvania stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 15 in half of years, as early as October 1 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 12 days later, around October 27; in spring the one-in-ten date for 28°F is April 27, 12 days before the 32°F one. The freeze-free season lasts 173 days in a typical year, shorter than at 53% of the 176 Pennsylvania stations; it reaches 193 days one year in ten and falls short of 151 one year in ten. On average 137 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 4, and return around October 4. Severe cold of 16°F or below comes every winter, usually between December 6 and March 5.

July is the warmest month at Graterford 1 E, PA, averaging 86°F by day and 64°F at night; January is the coldest at 40°F and 20°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 32% of years.

Warmth for growing adds up to 3,234 growing degree days a year (base 50°F), more than at 75% of the 176 Pennsylvania stations. 33% of them (1,078) have built up by the end of June, and July adds the most, 773. Precipitation totals 48.6 inches a year, most in July (5.0") and least in February (2.6"); May to September bring 47% of it.

The nearest other station, Phoenixville 1 E, PA, 5 miles southwest of Collegeville and 194 feet lower, has a last frost 6 days earlier (April 18), a first frost 12 days later (October 27), a season 19 days longer.

The first measurable snow (0.1 inch or more) in Collegeville usually arrives around January 12, and the last of the season around March 1. Those are the middle dates across the winters of 1991–2020 at Graterford 1 E, PA, 3.3 miles away: half of years saw snow earlier, half later. Snow fell in 88% of those winters. The last 32°F night of spring typically comes 54 days after the last snow.

ZIP 19426 is 3 miles from Graterford 1 E, PA, which stands at 279 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 19446 (Lansdale). The 2023 USDA Plant Hardiness Zone Map lists ZIP 19426 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.