Frost Dates for 03057 — Mont Vernon, New Hampshire

Half of springs at Milford, NH see their last 32°F night by May 3; only one in ten is past it by April 22, and one in ten still has one after May 15. Planting tender crops after May 7 leaves a 30% risk of a frost on them, after May 10 20%, and after May 15 10%. The 12 days between the even-odds date and the one-in-ten date is narrower than at 88% of the 51 New Hampshire stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 5 in half of years, as early as September 25 one year in ten, and holds off past October 18 one year in ten. A hard freeze of 28°F follows 11 days later, around October 16; 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 156 days in a typical year, longer than at 65% of the 51 New Hampshire stations; it reaches 173 days one year in ten and falls short of 138 one year in ten. On average 159 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 10 days longer, to about May 13, and return around September 28. Severe cold of 16°F or below comes every winter, usually between November 22 and March 20.

July is the warmest month at Milford, NH, averaging 83°F by day and 60°F at night; January is the coldest at 33°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 60% of years.

Warmth for growing adds up to 2,495 growing degree days a year (base 50°F), more than at 78% of the 51 New Hampshire stations. 31% of them (781) have built up by the end of June, and July adds the most, 674. Precipitation totals 46.1 inches a year, most in October (4.9") and least in January (3.0"); May to September bring 41% of it.

The nearest other station, E Milford, NH, 6 miles southeast of Mont Vernon, has a last frost 5 days earlier (April 28), a first frost 3 days later (October 8), a season 5 days longer.

The first measurable snow (0.1 inch or more) in Mont Vernon usually arrives around November 25, and the last of the season around March 26. Those are the middle dates across the winters of 1991–2020 at Milford, NH, 4.5 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 38 days after the last snow.

ZIP 03057 is 5 miles from Milford, NH, which stands at 320 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 03055 (Milford). The 2023 USDA Plant Hardiness Zone Map lists ZIP 03057 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.