USDA Hardiness Zone 6a
Frost Dates for 03086 — Wilton, New Hampshire
NOAA 1991–2020 normals from Greenville 1 NNE, NH (900 ft), 3 miles south.
Updated
In Wilton, the last spring frost (32°F) is around May 10 in half of years and has passed by May 27 in nine years out of ten. The first fall frost comes around October 6, as early as September 25 one year in ten, leaving a typical freeze-free season of 147 days (NOAA, Greenville 1 NNE, NH).
- Last spring frost
- May 10
- First fall frost
- October 6
- Growing season
- 147 days
- Hardiness zone
- 6a
50% probability
50% probability
freeze-free, 50%
-10 to -5°F (-23.3 to -20.6°C) coldest night
- First snow
- November 24
- Last snow
- April 2
- Winters with snow
- 100%
- Snow per year
- 75.4"
median, 1991–2020
median, 1991–2020
26 of 26 observed
NOAA normal
Frost risk by date in Wilton
Half of springs at Greenville 1 NNE, NH see their last 32°F night by May 10; only one in ten is past it by April 26, and one in ten still has one after May 27. Planting tender crops after May 17 leaves a 30% risk of a frost on them, after May 20 20%, and after May 27 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 98% 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 21 one year in ten. A hard freeze of 28°F follows 12 days later, around October 18; in spring the one-in-ten date for 28°F is May 13, 14 days before the 32°F one. The freeze-free season lasts 147 days in a typical year, shorter than at 59% of the 51 New Hampshire stations; it reaches 168 days one year in ten and falls short of 128 one year in ten. On average 157 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 23, and return around September 28. Severe cold of 16°F or below comes every winter, usually between November 28 and March 22.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 7 | May 13 | May 17 | May 20 | May 23 | May 26 | May 30 | Jun 3 | Jun 9 |
| 32°F | Apr 26 | Apr 30 | May 3 | May 6 | May 10 | May 13 | May 17 | May 20 | May 27 |
| 28°F | Apr 12 | Apr 17 | Apr 20 | Apr 23 | Apr 26 | Apr 30 | May 2 | May 6 | May 13 |
| 24°F | Mar 31 | Apr 2 | Apr 4 | Apr 6 | Apr 9 | Apr 11 | Apr 14 | Apr 18 | Apr 23 |
| 20°F | Mar 17 | Mar 22 | Mar 26 | Mar 30 | Mar 31 | Apr 1 | Apr 3 | Apr 5 | Apr 8 |
| 16°F | Mar 8 | Mar 13 | Mar 16 | Mar 19 | Mar 22 | Mar 25 | Mar 28 | Mar 31 | Apr 3 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 13 | Sep 18 | Sep 22 | Sep 25 | Sep 28 | Sep 30 | Oct 1 | Oct 4 | Oct 8 |
| 32°F | Sep 25 | Sep 29 | Oct 1 | Oct 3 | Oct 6 | Oct 8 | Oct 11 | Oct 15 | Oct 21 |
| 28°F | Oct 2 | Oct 7 | Oct 10 | Oct 15 | Oct 18 | Oct 21 | Oct 25 | Oct 30 | Nov 3 |
| 24°F | Oct 16 | Oct 21 | Oct 26 | Oct 29 | Nov 1 | Nov 4 | Nov 7 | Nov 12 | Nov 19 |
| 20°F | Oct 28 | Nov 2 | Nov 6 | Nov 10 | Nov 14 | Nov 18 | Nov 23 | Nov 28 | Dec 2 |
| 16°F | Nov 11 | Nov 17 | Nov 22 | Nov 25 | Nov 28 | Dec 1 | Dec 3 | Dec 7 | Dec 12 |
Freeze probabilities 1991–2020 at Greenville 1 NNE, NH, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 03086 →Compare Wilton with another place →
Weather by month in Wilton
July is the warmest month at Greenville 1 NNE, NH, averaging 79°F by day and 58°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 75% of years.
Warmth for growing adds up to 2,103 growing degree days a year (base 50°F), fewer than at 69% of the 51 New Hampshire stations. 29% of them (619) have built up by the end of June, and July adds the most, 582. Precipitation totals 49.6 inches a year, most in October (5.4") and least in February (3.3"); May to September bring 40% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 30 | 14 | 3.4 | 100% | 30 | 0 |
| Feb | 34 | 15 | 3.3 | 100% | 27 | 0 |
| Mar | 42 | 22 | 4.3 | 100% | 26 | 7 |
| Apr | 55 | 33 | 4.4 | 100% | 15 | 42 |
| May | 66 | 42 | 3.7 | 75% | 2 | 178 |
| Jun | 74 | 52 | 4.3 | 7% | 0 | 392 |
| Jul | 79 | 58 | 3.6 | 0% | 0 | 582 |
| Aug | 78 | 56 | 3.8 | 0% | 0 | 519 |
| Sep | 70 | 49 | 4.3 | 25% | <1 | 299 |
| Oct | 58 | 38 | 5.4 | 97% | 7 | 70 |
| Nov | 46 | 30 | 4.1 | 100% | 22 | 13 |
| Dec | 36 | 20 | 5.0 | 100% | 28 | 1 |
Monthly normals 1991–2020 at Greenville 1 NNE, NH (900 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Milford, NH, 7 miles east of Wilton and 580 feet lower, has a last frost 7 days earlier (May 3), a first frost 1 day earlier (October 5), a season 9 days longer.
When it snows in Wilton, New Hampshire
The first measurable snow (0.1 inch or more) in Wilton usually arrives around November 24, and the last of the season around April 2. Those are the middle dates across the winters of 1991–2020 at Greenville 1 NNE, NH, 3.4 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 38 days after the last snow.
Planting calendar for 03086
| When | What to do |
|---|---|
| March 1 – March 15 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 15 – March 29 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 12 – April 26 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 10 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 14 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 22 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 6 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 03086 is 3 miles from Greenville 1 NNE, NH, which stands at 900 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 03071 (New Ipswich). The 2023 USDA Plant Hardiness Zone Map lists ZIP 03086 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.
Frost dates across New Hampshire →
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.