Frost Dates for 19310 — Atglen, Pennsylvania

Half of springs at Coatesville 2 W, PA see their last 32°F night by April 19; 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 24 leaves a 30% risk of a frost on them, after April 29 20%, and after May 4 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 25 in half of years, as early as October 11 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 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 190 days in a typical year, longer than at 80% of the 176 Pennsylvania stations; it reaches 208 days one year in ten and falls short of 169 one year in ten. On average 120 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 1, and return around October 13. Severe cold of 16°F or below comes every winter, usually between December 18 and March 1.

July is the warmest month at Coatesville 2 W, PA, averaging 85°F by day and 65°F at night; January is the coldest at 39°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 16% of years.

Warmth for growing adds up to 3,302 growing degree days a year (base 50°F), more than at 80% of the 176 Pennsylvania stations. 34% of them (1,108) have built up by the end of June, and July adds the most, 775. Precipitation totals 52.2 inches a year, most in September (5.2") and least in February (3.3"); May to September bring 44% of it.

The nearest other station, New Holland 2 SE, PA, 10 miles northwest of Atglen, has a last frost 5 days earlier (April 14), a first frost 7 days later (November 1), a season 8 days longer.

The first measurable snow (0.1 inch or more) in Atglen usually arrives around December 10, and the last of the season around April 5. Those are the middle dates across the winters of 1991–2020 at Coatesville 2 W, PA, 6.4 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 14 days after the last snow.

ZIP 19310 is 6 miles from Coatesville 2 W, PA, which stands at 640 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 19320 (Coatesville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 19310 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.