Frost Dates for 03447 — Fitzwilliam, New Hampshire

Half of springs at Jaffrey Municipal Airport, NH see their last 32°F night by May 5; only one in ten is past it by April 23, and one in ten still has one after May 20. Planting tender crops after May 11 leaves a 30% risk of a frost on them, after May 15 20%, and after May 20 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 76% of the 51 New Hampshire stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 6 in half of years, as early as September 25 one year in ten, and holds off past October 22 one year in ten. A hard freeze of 28°F follows 14 days later, around October 20; in spring the one-in-ten date for 28°F is May 6, 14 days before the 32°F one. The freeze-free season lasts 152 days in a typical year, longer than at 61% of the 51 New Hampshire stations; it reaches 171 days one year in ten and falls short of 134 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 13 days longer, to about May 18, and return around September 26. Severe cold of 16°F or below comes every winter, usually between November 27 and March 24.

July is the warmest month at Jaffrey Municipal Airport, NH, averaging 81°F by day and 59°F at night; January is the coldest at 31°F and 13°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 68% of years.

Warmth for growing adds up to 2,276 growing degree days a year (base 50°F), more than at 55% of the 51 New Hampshire stations. 30% of them (689) have built up by the end of June, and July adds the most, 614. Precipitation totals 46.4 inches a year, most in October (4.8") and least in January (3.0"); May to September bring 44% of it.

The nearest other station, Jaffrey Silver Rch Airpark, NH, 8 miles northeast of Fitzwilliam, has the same 50% last-frost date, the same first-frost date, a season 2 days longer.

The first measurable snow (0.1 inch or more) in Fitzwilliam usually arrives around November 15, and the last of the season around March 24. Those are the middle dates across the winters of 1991–2020 at Fitzwilliam 2 W, NH, 2.3 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 42 days after the last snow.

ZIP 03447 is 8 miles from Jaffrey Municipal Airport, NH, which stands at 1,040 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 03461 (Rindge). The 2023 USDA Plant Hardiness Zone Map lists ZIP 03447 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.