USDA Hardiness Zone 6a
Frost Dates for 03261 — Northwood, New Hampshire
NOAA 1991–2020 normals from Durham, NH (75 ft), 14 miles east.
Updated
In Northwood, the last spring frost (32°F) is around May 8 in half of years and has passed by May 22 in nine years out of ten. The first fall frost comes around October 4, as early as September 23 one year in ten, leaving a typical freeze-free season of 148 days (NOAA, Durham, NH).
- Last spring frost
- May 8
- First fall frost
- October 4
- Growing season
- 148 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
- December 5
- Last snow
- March 20
- Winters with snow
- 100%
- Snow per year
- 38.9"
median, 1991–2020
median, 1991–2020
29 of 29 observed
NOAA normal
Frost risk by date in Northwood
Half of springs at Durham, NH see their last 32°F night by May 8; only one in ten is past it by April 27, and one in ten still has one after May 22. Planting tender crops after May 14 leaves a 30% risk of a frost on them, after May 18 20%, and after May 22 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 25% of the 51 New Hampshire stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 4 in half of years, as early as September 23 one year in ten, and holds off past October 20 one year in ten. A hard freeze of 28°F follows 11 days later, around October 15; in spring the one-in-ten date for 28°F is May 10, 12 days before the 32°F one. The freeze-free season lasts 148 days in a typical year, shorter than at 49% of the 51 New Hampshire stations; it reaches 164 days one year in ten and falls short of 131 one year in ten. On average 151 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 May 20, and return around September 26. Severe cold of 16°F or below comes every winter, usually between November 26 and March 22.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 7 | May 11 | May 15 | May 18 | May 20 | May 23 | May 26 | May 29 | Jun 2 |
| 32°F | Apr 27 | Apr 30 | May 3 | May 6 | May 8 | May 11 | May 14 | May 18 | May 22 |
| 28°F | Apr 13 | Apr 18 | Apr 22 | Apr 24 | Apr 27 | Apr 29 | May 2 | May 4 | May 10 |
| 24°F | Mar 31 | Apr 3 | Apr 6 | Apr 8 | Apr 10 | Apr 14 | Apr 17 | Apr 20 | Apr 25 |
| 20°F | Mar 17 | Mar 22 | Mar 27 | Mar 30 | Apr 1 | Apr 2 | Apr 5 | Apr 7 | Apr 11 |
| 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 12 | Sep 17 | Sep 20 | Sep 23 | Sep 26 | Sep 28 | Oct 1 | Oct 3 | Oct 6 |
| 32°F | Sep 23 | Sep 28 | Oct 1 | Oct 2 | Oct 4 | Oct 7 | Oct 10 | Oct 14 | Oct 20 |
| 28°F | Oct 2 | Oct 6 | Oct 9 | Oct 13 | Oct 15 | Oct 19 | Oct 23 | Oct 27 | Nov 2 |
| 24°F | Oct 13 | Oct 18 | Oct 22 | Oct 26 | Oct 30 | Nov 1 | Nov 5 | Nov 8 | Nov 14 |
| 20°F | Oct 27 | Nov 1 | Nov 5 | Nov 9 | Nov 12 | Nov 15 | Nov 18 | Nov 22 | Nov 28 |
| 16°F | Nov 12 | Nov 17 | Nov 20 | Nov 23 | Nov 26 | Nov 29 | Dec 1 | Dec 4 | Dec 9 |
Freeze probabilities 1991–2020 at Durham, 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 03261 →Compare Northwood with another place →
Weather by month in Northwood
July is the warmest month at Durham, NH, averaging 83°F by day and 59°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 79% of years.
Warmth for growing adds up to 2,445 growing degree days a year (base 50°F), more than at 71% of the 51 New Hampshire stations. 30% of them (731) have built up by the end of June, and July adds the most, 646. Precipitation totals 45.3 inches a year, most in October (4.7") and least in January (2.7"); May to September bring 43% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 33 | 14 | 2.7 | 100% | 30 | 1 |
| Feb | 36 | 16 | 3.0 | 100% | 26 | 0 |
| Mar | 45 | 24 | 3.5 | 100% | 25 | 6 |
| Apr | 58 | 34 | 4.1 | 100% | 14 | 55 |
| May | 68 | 44 | 3.6 | 79% | 3 | 211 |
| Jun | 77 | 53 | 4.0 | 0% | 0 | 458 |
| Jul | 83 | 59 | 4.0 | 0% | 0 | 646 |
| Aug | 81 | 57 | 3.8 | 0% | 0 | 597 |
| Sep | 73 | 50 | 4.0 | 29% | 1 | 360 |
| Oct | 61 | 39 | 4.7 | 97% | 8 | 95 |
| Nov | 48 | 30 | 3.9 | 100% | 18 | 14 |
| Dec | 38 | 21 | 4.0 | 100% | 27 | 1 |
Monthly normals 1991–2020 at Durham, NH (75 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, Epping, NH, 14 miles southeast of Northwood, has a last frost 1 day earlier (May 7), the same first-frost date.
When it snows in Northwood, New Hampshire
The first measurable snow (0.1 inch or more) in Northwood usually arrives around December 5, and the last of the season around March 20. Those are the middle dates across the winters of 1991–2020 at Durham, NH, 13.9 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 49 days after the last snow.
Planting calendar for 03261
| When | What to do |
|---|---|
| February 27 – March 13 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 13 – March 27 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 10 – April 24 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 8 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 12 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 20 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 4 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 03261 is 14 miles from Durham, NH, which stands at 75 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 03824 (Durham). The 2023 USDA Plant Hardiness Zone Map lists ZIP 03261 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.