Frost Dates for 17313 — Dallastown, Pennsylvania

Half of springs at York 3 SSW Pump Stn, PA see their last 32°F night by April 26; only one in ten is past it by April 7, and one in ten still has one after May 13. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 7 20%, and after May 13 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 50% of the 176 Pennsylvania stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 19 in half of years, as early as October 5 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 31; in spring the one-in-ten date for 28°F is April 26, 17 days before the 32°F one. The freeze-free season lasts 177 days in a typical year, longer than at 56% of the 176 Pennsylvania stations; it reaches 200 days one year in ten and falls short of 155 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 8, and return around October 8. Severe cold of 16°F or below comes every winter, usually between December 9 and March 5.

July is the warmest month at York 3 SSW Pump Stn, PA, averaging 88°F by day and 63°F at night; January is the coldest at 41°F and 21°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 35% of years.

Warmth for growing adds up to 3,556 growing degree days a year (base 50°F), more than at 92% of the 176 Pennsylvania stations. 35% of them (1,257) have built up by the end of June, and July adds the most, 787. Precipitation totals 46.4 inches a year, most in September (5.1") and least in February (2.8"); May to September bring 48% of it.

The nearest other station, York Airport, PA, 12 miles west of Dallastown, has a last frost 1 day later (April 27), a first frost 1 day earlier (October 18), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Dallastown usually arrives around December 19, and the last of the season around March 17. Those are the middle dates across the winters of 1991–2020 at York 3 SSW Pump Stn, PA, 5.7 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 40 days after the last snow.

ZIP 17313 is 6 miles from York 3 SSW Pump Stn, PA, which stands at 390 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 17403 (York). The 2023 USDA Plant Hardiness Zone Map lists ZIP 17313 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.