USDA Hardiness Zone 6a
Frost Dates for 03244 — Hillsboro, New Hampshire
NOAA 1991–2020 normals from Weare 2 NE, NH (805 ft), 8 miles east.
Updated
In Hillsboro, the last spring frost (32°F) is around May 9 in half of years and has passed by May 23 in nine years out of ten. The first fall frost comes around October 5, as early as September 25 one year in ten, leaving a typical freeze-free season of 148 days (NOAA, Weare 2 NE, NH).
- Last spring frost
- May 9
- First fall frost
- October 5
- 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
- November 18
- Last snow
- March 28
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
15 of 15 observed
NOAA normal
Frost risk by date in Hillsboro
Half of springs at Weare 2 NE, NH see their last 32°F night by May 9; only one in ten is past it by April 27, and one in ten still has one after May 23. Planting tender crops after May 15 leaves a 30% risk of a frost on them, after May 19 20%, and after May 23 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 5 in half of years, as early as September 25 one year in ten, and holds off past October 17 one year in ten. A hard freeze of 28°F follows 8 days later, around October 13; in spring the one-in-ten date for 28°F is May 13, 10 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 130 one year in ten. On average 172 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 21, and return around September 26. Severe cold of 16°F or below comes every winter, usually between November 18 and March 28.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 7 | May 12 | May 16 | May 19 | May 21 | May 25 | May 28 | Jun 1 | Jun 5 |
| 32°F | Apr 27 | May 1 | May 4 | May 7 | May 9 | May 12 | May 15 | May 19 | May 23 |
| 28°F | Apr 18 | Apr 21 | Apr 24 | Apr 27 | Apr 29 | May 1 | May 3 | May 7 | May 13 |
| 24°F | Apr 5 | Apr 8 | Apr 12 | Apr 15 | Apr 17 | Apr 19 | Apr 22 | Apr 25 | Apr 30 |
| 20°F | Mar 23 | Mar 30 | Apr 1 | Apr 3 | Apr 4 | Apr 6 | Apr 9 | Apr 14 | Apr 18 |
| 16°F | Mar 12 | Mar 17 | Mar 20 | Mar 24 | Mar 28 | Mar 31 | Apr 1 | Apr 3 | Apr 6 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 15 | Sep 19 | Sep 22 | Sep 23 | Sep 26 | Sep 28 | Oct 1 | Oct 3 | Oct 6 |
| 32°F | Sep 25 | Sep 28 | Oct 1 | Oct 2 | Oct 5 | Oct 6 | Oct 9 | Oct 12 | Oct 17 |
| 28°F | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 13 | Oct 16 | Oct 19 | Oct 23 | Oct 29 |
| 24°F | Oct 11 | Oct 15 | Oct 18 | Oct 21 | Oct 25 | Oct 27 | Oct 31 | Nov 4 | Nov 8 |
| 20°F | Oct 20 | Oct 26 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 12 | Nov 16 | Nov 21 |
| 16°F | Nov 3 | Nov 7 | Nov 12 | Nov 15 | Nov 18 | Nov 22 | Nov 25 | Nov 29 | Dec 4 |
Freeze probabilities 1991–2020 at Weare 2 NE, 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 03244 →Compare Hillsboro with another place →
Compared with the next station
The nearest other station, Weare, NH, 10 miles east of Hillsboro, has a last frost 7 days earlier (May 2), a first frost 3 days later (October 8), a season 10 days longer.
When it snows in Hillsboro, New Hampshire
The first measurable snow (0.1 inch or more) in Hillsboro usually arrives around November 18, and the last of the season around March 28. Those are the middle dates across the winters of 1991–2020 at Weare, NH, 9.5 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.
Planting calendar for 03244
| When | What to do |
|---|---|
| February 28 – March 14 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 14 – March 28 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 11 – April 25 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 9 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 13 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 21 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 5 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 03244 is 8 miles from Weare 2 NE, NH, which stands at 805 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 03244 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.