Frost Dates for 07928 — Chatham, New Jersey

Half of springs at Canoe Brook, NJ see their last 32°F night by April 18; only one in ten is past it by April 3, and one in ten still has one after May 6. Planting tender crops after April 27 leaves a 30% risk of a frost on them, after May 1 20%, and after May 6 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 80% of the 56 New Jersey stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 27 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 6; in spring the one-in-ten date for 28°F is April 19, 17 days before the 32°F one. The freeze-free season lasts 189 days in a typical year, shorter than at 59% of the 56 New Jersey stations; it reaches 212 days one year in ten and falls short of 166 one year in ten. On average 118 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 April 30, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 21 and February 28.

July is the warmest month at Canoe Brook, NJ, averaging 86°F by day and 66°F at night; January is the coldest at 40°F and 22°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 20% of years.

Warmth for growing adds up to 3,434 growing degree days a year (base 50°F), fewer than at 54% of the 56 New Jersey stations. 33% of them (1,128) have built up by the end of June, and July adds the most, 804. Precipitation totals 50.4 inches a year, most in August (4.9") and least in February (3.0"); May to September bring 46% of it.

The nearest other station, Cranford, NJ, 6 miles southeast of Chatham, has a last frost 7 days earlier (April 11), a first frost 4 days later (October 31), a season 13 days longer.

The first measurable snow (0.1 inch or more) in Chatham usually arrives around December 20, and the last of the season around March 18. Those are the middle dates across the winters of 1991–2020 at Canoe Brook, NJ, 2.4 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 31 days after the last snow.

ZIP 07928 is 2 miles from Canoe Brook, NJ, which stands at 180 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 10 other ZIP codes share the station; its figures are presented in full for 07960 (Morristown). The 2023 USDA Plant Hardiness Zone Map lists ZIP 07928 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.