Frost Dates for 17821 — Danville, Pennsylvania

Half of springs at Sunbury, PA see their last 32°F night by April 30; only one in ten is past it by April 15, and one in ten still has one after May 19. Planting tender crops after May 7 leaves a 30% risk of a frost on them, after May 12 20%, and after May 19 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 90% of the 176 Pennsylvania stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 13 in half of years, as early as September 30 one year in ten, and holds off past October 31 one year in ten. A hard freeze of 28°F follows 13 days later, around October 26; in spring the one-in-ten date for 28°F is May 4, 15 days before the 32°F one. The freeze-free season lasts 166 days in a typical year, shorter than at 66% of the 176 Pennsylvania stations; it reaches 188 days one year in ten and falls short of 143 one year in ten. On average 134 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 11 days longer, to about May 11, and return around October 1. Severe cold of 16°F or below comes every winter, usually between December 3 and March 14.

July is the warmest month at Sunbury, PA, averaging 84°F by day and 60°F at night; January is the coldest at 35°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 August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 44% of years.

Warmth for growing adds up to 2,859 growing degree days a year (base 50°F), fewer than at 59% of the 176 Pennsylvania stations. 34% of them (971) have built up by the end of June, and July adds the most, 693. Precipitation totals 43.6 inches a year, most in September (4.5") and least in February (2.3"); May to September bring 48% of it.

The nearest other station, Lewisburg, PA, 13 miles west of Danville, has a last frost 4 days earlier (April 26), a first frost 7 days later (October 20), a season 10 days longer.

The first measurable snow (0.1 inch or more) in Danville usually arrives around December 23, and the last of the season around March 20. Those are the middle dates across the winters of 1991–2020 at Danville, PA, 2 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 41 days after the last snow.

ZIP 17821 is 12 miles from Sunbury, PA, which stands at 575 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 17821 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.