Frost Dates for 19312 — Berwyn, Pennsylvania

Half of springs at Phoenixville 1 E, PA see their last 32°F night by April 18; only one in ten is past it by April 3, and one in ten still has one after May 4. Planting tender crops after April 25 leaves a 30% risk of a frost on them, after April 29 20%, and after May 4 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 27 in half of years, as early as October 12 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 10 days later, around November 6; in spring the one-in-ten date for 28°F is April 18, 16 days before the 32°F one. The freeze-free season lasts 192 days in a typical year, longer than at 83% of the 176 Pennsylvania stations; it reaches 212 days one year in ten and falls short of 168 one year in ten. On average 117 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 April 30, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 18 and February 28.

July is the warmest month at Phoenixville 1 E, PA, averaging 88°F by day and 66°F at night; January is the coldest at 41°F and 23°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 16% of years.

Warmth for growing adds up to 3,668 growing degree days a year (base 50°F), more than at 94% of the 176 Pennsylvania stations. 34% of them (1,262) have built up by the end of June, and July adds the most, 834. Precipitation totals 45.3 inches a year, most in July (4.6") and least in February (2.9"); May to September bring 45% of it.

The nearest other station, Norristown, PA, 8 miles northeast of Berwyn, has a last frost 10 days earlier (April 8), a first frost 4 days later (October 31), a season 11 days longer.

The first measurable snow (0.1 inch or more) in Berwyn usually arrives around December 11, and the last of the season around March 4. Those are the middle dates across the winters of 1991–2020 at Norristown, PA, 7.8 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 45 days after the last snow.

ZIP 19312 is 6 miles from Phoenixville 1 E, PA, which stands at 85 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 19460 (Phoenixville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 19312 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.