Frost Dates for 08629 — Trenton, New Jersey

Half of springs at Trenton State College, NJ see their last 32°F night by April 17; only one in ten is past it by April 2, and one in ten still has one after May 6. Planting tender crops after April 25 leaves a 30% risk of a frost on them, after April 30 20%, and after May 6 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 91% of the 56 New Jersey stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 28 in half of years, as early as October 11 one year in ten, and holds off past November 10 one year in ten. A hard freeze of 28°F follows 10 days later, around November 7; in spring the one-in-ten date for 28°F is April 17, 19 days before the 32°F one. The freeze-free season lasts 192 days in a typical year, shorter than at 52% of the 56 New Jersey stations; it reaches 214 days one year in ten and falls short of 168 one year in ten. On average 109 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 14 days longer, to about May 1, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 14 and February 28.

July is the warmest month at Trenton State College, NJ, averaging 87°F by day and 65°F at night; January is the coldest at 40°F and 23°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 18% of years.

Warmth for growing adds up to 3,400 growing degree days a year (base 50°F), fewer than at 57% of the 56 New Jersey stations. 33% of them (1,119) have built up by the end of June, and July adds the most, 798. Precipitation totals 47.3 inches a year, most in July (4.8") and least in February (2.8"); May to September bring 45% of it.

The nearest other station, Trenton Mercer Co Airport, NJ, 6 miles northwest of Trenton, has a last frost 7 days earlier (April 10), a first frost 4 days later (November 1), a season 10 days longer.

The first measurable snow (0.1 inch or more) in Trenton usually arrives around December 6, and the last of the season around March 22. Those are the middle dates across the winters of 1991–2020 at Trenton Mercer Co Airport, NJ, 5.9 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 08629 is 5 miles from Trenton State College, NJ, which stands at 100 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 19067 (Yardley). The 2023 USDA Plant Hardiness Zone Map lists ZIP 08629 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.