USDA Hardiness Zone 5b
Frost Dates for 03237 — Gilmanton, New Hampshire
NOAA 1991–2020 normals from Lakeport 2, NH (500 ft), 9 miles northwest.
Updated
In Gilmanton, the last spring frost (32°F) is around April 30 in half of years and has passed by May 13 in nine years out of ten. The first fall frost comes around October 18, as early as October 4 one year in ten, leaving a typical freeze-free season of 170 days (NOAA, Lakeport 2, NH).
- Last spring frost
- April 30
- First fall frost
- October 18
- Growing season
- 170 days
- Hardiness zone
- 5b
50% probability
50% probability
freeze-free, 50%
-15 to -10°F (-26.1 to -23.3°C) coldest night
- First snow
- December 2
- Last snow
- March 31
- Winters with snow
- 100%
- Snow per year
- 61.9"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Gilmanton
Half of springs at Lakeport 2, NH see their last 32°F night by April 30; only one in ten is past it by April 19, and one in ten still has one after May 13. Planting tender crops after May 4 leaves a 30% risk of a frost on them, after May 7 20%, and after May 13 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 67% of the 51 New Hampshire stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 18 in half of years, as early as October 4 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 14 days later, around November 1; in spring the one-in-ten date for 28°F is April 30, 13 days before the 32°F one. The freeze-free season lasts 170 days in a typical year, longer than at 92% of the 51 New Hampshire stations; it reaches 188 days one year in ten and falls short of 153 one year in ten. On average 150 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 10, and return around October 5. Severe cold of 16°F or below comes every winter, usually between December 1 and March 22.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 30 | May 3 | May 5 | May 8 | May 10 | May 12 | May 16 | May 18 | May 23 |
| 32°F | Apr 19 | Apr 23 | Apr 25 | Apr 28 | Apr 30 | May 2 | May 4 | May 7 | May 13 |
| 28°F | Apr 6 | Apr 10 | Apr 12 | Apr 14 | Apr 17 | Apr 20 | Apr 22 | Apr 25 | Apr 30 |
| 24°F | Mar 28 | Apr 1 | Apr 3 | Apr 4 | Apr 6 | Apr 8 | Apr 10 | Apr 14 | Apr 18 |
| 20°F | Mar 16 | Mar 21 | Mar 25 | Mar 29 | Mar 31 | Apr 1 | Apr 3 | Apr 5 | Apr 9 |
| 16°F | Mar 10 | Mar 14 | Mar 17 | Mar 20 | Mar 22 | Mar 25 | Mar 29 | Mar 31 | Apr 3 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 25 | Sep 29 | Oct 1 | Oct 4 | Oct 5 | Oct 8 | Oct 11 | Oct 15 | Oct 19 |
| 32°F | Oct 4 | Oct 8 | Oct 12 | Oct 14 | Oct 18 | Oct 20 | Oct 24 | Oct 28 | Nov 3 |
| 28°F | Oct 16 | Oct 21 | Oct 26 | Oct 29 | Nov 1 | Nov 3 | Nov 5 | Nov 8 | Nov 13 |
| 24°F | Oct 30 | Nov 2 | Nov 6 | Nov 8 | Nov 12 | Nov 14 | Nov 17 | Nov 21 | Nov 25 |
| 20°F | Nov 9 | Nov 13 | Nov 17 | Nov 20 | Nov 22 | Nov 25 | Nov 29 | Dec 1 | Dec 6 |
| 16°F | Nov 17 | Nov 22 | Nov 26 | Nov 29 | Dec 1 | Dec 4 | Dec 7 | Dec 11 | Dec 16 |
Freeze probabilities 1991–2020 at Lakeport 2, 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 03237 →Compare Gilmanton with another place →
Weather by month in Gilmanton
July is the warmest month at Lakeport 2, NH, averaging 82°F by day and 60°F at night; January is the coldest at 30°F and 12°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 46% of years.
Warmth for growing adds up to 2,482 growing degree days a year (base 50°F), more than at 76% of the 51 New Hampshire stations. 29% of them (732) have built up by the end of June, and July adds the most, 659. Precipitation totals 45.7 inches a year, most in October (4.8") and least in February (2.9"); May to September bring 44% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 30 | 12 | 3.1 | 100% | 30 | 0 |
| Feb | 34 | 13 | 2.9 | 100% | 27 | 0 |
| Mar | 43 | 21 | 3.4 | 100% | 28 | 3 |
| Apr | 56 | 33 | 3.7 | 100% | 14 | 38 |
| May | 68 | 45 | 3.5 | 46% | 1 | 219 |
| Jun | 77 | 55 | 4.4 | 0% | 0 | 472 |
| Jul | 82 | 60 | 4.6 | 0% | 0 | 659 |
| Aug | 81 | 59 | 3.9 | 0% | 0 | 612 |
| Sep | 73 | 52 | 3.8 | 3% | <1 | 375 |
| Oct | 60 | 40 | 4.8 | 85% | 5 | 94 |
| Nov | 47 | 30 | 3.7 | 100% | 18 | 9 |
| Dec | 36 | 20 | 3.9 | 100% | 28 | 0 |
Monthly normals 1991–2020 at Lakeport 2, NH (500 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, Franklin Falls Dam, NH, 14 miles west of Gilmanton, has a last frost 7 days later (May 7), a first frost 15 days earlier (October 3), a season 22 days shorter.
When it snows in Gilmanton, New Hampshire
The first measurable snow (0.1 inch or more) in Gilmanton usually arrives around December 2, and the last of the season around March 31. Those are the middle dates across the winters of 1991–2020 at Lakeport 2, NH, 9.4 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 30 days after the last snow.
Planting calendar for 03237
| When | What to do |
|---|---|
| February 19 – March 5 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 5 – March 19 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 2 – April 16 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 30 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 26 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 4 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 18 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 03237 is 9 miles from Lakeport 2, NH, which stands at 500 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 03246 (Laconia). The 2023 USDA Plant Hardiness Zone Map lists ZIP 03237 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°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.