USDA Hardiness Zone 6a
Frost Dates for 03051 — Hudson, New Hampshire
NOAA 1991–2020 normals from Hudson 1 SSE, NH (185 ft), 2 miles north.
Updated
In Hudson, the last spring frost (32°F) is around May 3 in half of years and has passed by May 16 in nine years out of ten. The first fall frost comes around October 8, as early as September 27 one year in ten, leaving a typical freeze-free season of 156 days (NOAA, Hudson 1 SSE, NH).
- Last spring frost
- May 3
- First fall frost
- October 8
- Growing season
- 156 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 21
- Last snow
- April 4
- Winters with snow
- 100%
- Snow per year
- 66.8"
median, 1991–2020
median, 1991–2020
24 of 24 observed
NOAA normal
Frost risk by date in Hudson
Half of springs at Hudson 1 SSE, NH see their last 32°F night by May 3; only one in ten is past it by April 24, and one in ten still has one after May 16. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 11 20%, and after May 16 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 8 in half of years, as early as September 27 one year in ten, and holds off past October 23 one year in ten. A hard freeze of 28°F follows 10 days later, around October 18; in spring the one-in-ten date for 28°F is May 5, 11 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 175 days one year in ten and falls short of 140 one year in ten. On average 162 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 30. Severe cold of 16°F or below comes every winter, usually between November 25 and March 21.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 2 | May 5 | May 8 | May 10 | May 13 | May 16 | May 19 | May 22 | May 26 |
| 32°F | Apr 24 | Apr 27 | Apr 29 | May 1 | May 3 | May 6 | May 8 | May 11 | May 16 |
| 28°F | Apr 9 | Apr 14 | Apr 18 | Apr 20 | Apr 22 | Apr 25 | Apr 27 | Apr 30 | May 5 |
| 24°F | Mar 30 | Apr 2 | Apr 4 | Apr 6 | Apr 9 | Apr 12 | Apr 15 | Apr 18 | Apr 22 |
| 20°F | Mar 14 | Mar 21 | Mar 25 | Mar 29 | Mar 31 | Apr 2 | Apr 3 | Apr 6 | Apr 11 |
| 16°F | Mar 7 | Mar 11 | Mar 15 | Mar 18 | Mar 21 | Mar 23 | Mar 26 | Mar 30 | Apr 1 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 17 | Sep 22 | Sep 24 | Sep 27 | Sep 30 | Oct 1 | Oct 3 | Oct 6 | Oct 10 |
| 32°F | Sep 27 | Oct 1 | Oct 2 | Oct 5 | Oct 8 | Oct 10 | Oct 13 | Oct 17 | Oct 23 |
| 28°F | Oct 4 | Oct 9 | Oct 12 | Oct 15 | Oct 18 | Oct 21 | Oct 25 | Oct 31 | Nov 3 |
| 24°F | Oct 15 | Oct 20 | Oct 24 | Oct 27 | Oct 31 | Nov 1 | Nov 5 | Nov 10 | Nov 14 |
| 20°F | Oct 27 | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 14 | Nov 17 | Nov 21 | Nov 26 |
| 16°F | Nov 10 | Nov 14 | Nov 17 | Nov 21 | Nov 25 | Nov 28 | Dec 1 | Dec 4 | Dec 10 |
Freeze probabilities 1991–2020 at Hudson 1 SSE, 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 03051 →Compare Hudson with another place →
Weather by month in Hudson
July is the warmest month at Hudson 1 SSE, NH, averaging 83°F by day and 61°F at night; January is the coldest at 34°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 63% of years.
Warmth for growing adds up to 2,631 growing degree days a year (base 50°F), more than at 88% of the 51 New Hampshire stations. 31% of them (813) have built up by the end of June, and July adds the most, 691. Precipitation totals 46.2 inches a year, most in October (4.7") and least in February (3.2"); May to September bring 40% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 34 | 13 | 3.3 | 100% | 30 | 1 |
| Feb | 37 | 14 | 3.2 | 100% | 27 | 0 |
| Mar | 45 | 23 | 4.2 | 100% | 26 | 7 |
| Apr | 58 | 34 | 4.1 | 100% | 15 | 59 |
| May | 69 | 46 | 3.6 | 63% | 2 | 246 |
| Jun | 78 | 56 | 4.2 | 0% | 0 | 500 |
| Jul | 83 | 61 | 3.3 | 0% | 0 | 691 |
| Aug | 82 | 59 | 3.8 | 0% | 0 | 634 |
| Sep | 74 | 51 | 3.7 | 18% | 1 | 380 |
| Oct | 61 | 38 | 4.7 | 97% | 11 | 97 |
| Nov | 49 | 28 | 3.7 | 100% | 22 | 14 |
| Dec | 39 | 20 | 4.4 | 100% | 29 | 1 |
Monthly normals 1991–2020 at Hudson 1 SSE, NH (185 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, Nashua 2 NNW, NH, 3 miles northwest of Hudson, has a last frost 3 days earlier (April 30), a first frost 4 days later (October 12), a season 9 days longer.
When it snows in Hudson, New Hampshire
The first measurable snow (0.1 inch or more) in Hudson usually arrives around November 21, and the last of the season around April 4. Those are the middle dates across the winters of 1991–2020 at Hudson 1 SSE, NH, 1.6 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 29 days after the last snow.
Planting calendar for 03051
| When | What to do |
|---|---|
| February 22 – March 8 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 8 – March 22 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 5 – April 19 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 3 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 16 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 24 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 8 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 03051 is 2 miles from Hudson 1 SSE, NH, which stands at 185 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 03051 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.