Frost Dates for 12138 — Petersburg, New York

Half of springs at Grafton, NY see their last 32°F night by May 1; only one in ten is past it by April 18, and one in ten still has one after May 15. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 10 20%, and after May 15 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 63% of the 173 New York stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 11 in half of years, as early as September 28 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 14 days later, around October 25; in spring the one-in-ten date for 28°F is May 2, 13 days before the 32°F one. The freeze-free season lasts 162 days in a typical year, shorter than at 50% of the 173 New York stations; it reaches 181 days one year in ten and falls short of 142 one year in ten. On average 152 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 13 days longer, to about May 14, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 27 and March 23.

July is the warmest month at Grafton, NY, averaging 78°F by day and 59°F at night; January is the coldest at 30°F and 14°F. A freezing night is all but certain in every month from October 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 51% of years.

Warmth for growing adds up to 2,235 growing degree days a year (base 50°F), fewer than at 72% of the 173 New York stations. 32% of them (707) have built up by the end of June, and July adds the most, 572. Precipitation totals 47.1 inches a year, most in October (4.7") and least in February (2.6"); May to September bring 45% of it.

The nearest other station, Pownal 1 NE, VT, 8 miles east of Petersburg and 450 feet lower, has a last frost 6 days later (May 7), a first frost 3 days earlier (October 8), a season 8 days shorter.

The first measurable snow (0.1 inch or more) in Petersburg usually arrives around November 9, and the last of the season around April 5. Those are the middle dates across the winters of 1991–2020 at Pownal 1 NE, VT, 7.7 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 26 days after the last snow.

ZIP 12138 is 5 miles from Grafton, NY, which stands at 1,560 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 12018 (Averill Park). The 2023 USDA Plant Hardiness Zone Map lists ZIP 12138 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.