Frost Dates for 17325 — Gettysburg, Pennsylvania

Half of springs at Eisenhower Nhs, PA see their last 32°F night by April 24; only one in ten is past it by April 7, and one in ten still has one after May 10. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 4 20%, and after May 10 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 21 in half of years, as early as October 6 one year in ten, and holds off past November 4 one year in ten. A hard freeze of 28°F follows 11 days later, around November 1; in spring the one-in-ten date for 28°F is April 27, 13 days before the 32°F one. The freeze-free season lasts 180 days in a typical year, longer than at 64% of the 176 Pennsylvania stations; it reaches 201 days one year in ten and falls short of 158 one year in ten. On average 121 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 5, and return around October 10. Severe cold of 16°F or below comes every winter, usually between December 10 and March 4.

July is the warmest month at Eisenhower Nhs, PA, averaging 86°F by day and 63°F at night; January is the coldest at 40°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 30% of years.

Warmth for growing adds up to 3,276 growing degree days a year (base 50°F), more than at 78% of the 176 Pennsylvania stations. 34% of them (1,106) have built up by the end of June, and July adds the most, 759. Precipitation totals 44.3 inches a year, most in June (4.7") and least in February (2.7"); May to September bring 48% of it.

The nearest other station, Cashtown 1S, PA, 7 miles northwest of Gettysburg and 170 feet higher, has a last frost 4 days later (April 28), a first frost 4 days earlier (October 17), a season 10 days shorter.

The first measurable snow (0.1 inch or more) in Gettysburg usually arrives around December 26, and the last of the season around March 4. Those are the middle dates across the winters of 1991–2020 at Eisenhower Nhs, PA, 1.5 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 51 days after the last snow.

ZIP 17325 is 2 miles from Eisenhower Nhs, PA, which stands at 540 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 17325 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.