Frost dates for ZIP 03801 (Portsmouth, NH)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Greenland, NH (4 miles away).
- Average last spring frostMay 450% chance of a 32°F freeze after this date
- Average first fall frostOct 850% chance of a 32°F freeze by this date
- Growing season (frost-free)157 daysmedian, 32°F threshold
- USDA hardiness zone6a-10 to -5°F avg. coldest night
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This week in your yard
As of Oct 17, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
52°F 50–55°F
24-hour average · latest 49°F, as of Oct 17, 10:00 PM CDT
Measured at NOAA USCRN station Durham 2 SSW, 8 mi away. Daily averages: Wed 56°, Thu 54°, Fri 53°.
4-inch depth
54°F 50–55°F
24-hour average · latest 52°F, as of Oct 17, 10:00 PM CDT
Measured at NOAA USCRN station Durham 2 SSW, 8 mi away. Daily averages: Wed 55°, Thu 55°, Fri 54°.
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
The latest National Weather Service 7-day forecast and any Frost Advisory or Freeze Warning for 03801 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 54°F at 4 inches. Fall pre-emergent window is mostly past. Next: spring, when soil reaches 50°F (typically mid-April to early May).
Fertilizer window
Lawn region: North (cool-season). Timing only; always follow the product label.
- Kentucky bluegrass (cool-season): Early fall: Around Labor Day (late August–September); Late fall: Late October–November, before the ground freezes; Late spring: Optional around Memorial Day. Avoid: Early-spring and midsummer feeding (pushes top growth, favors crabgrass).
Plant now
No vegetable planting windows are open this week.
Prune now
No frost-timed pruning windows are open this week.
Spring-flowering shrubs are pruned right after their flowers fade, not by date. See the pruning guide.
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | Apr 23 |
| 50% (the "average" last frost) | May 4 |
| 10% (cautious: only 1 year in 10 freezes later) | May 18 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Sep 27 |
| 50% (the "average" first frost) | Oct 8 |
| 90% (late: most years have frozen by now) | Oct 24 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 16 | Sep 30 |
| 32°F (freeze) | May 4 | Oct 8 |
| 28°F (hard freeze) | Apr 23 | Oct 21 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
Vegetable planting calendar for 03801
Dates count from your average last spring frost (May 4) and first fall frost (Oct 8). Half of years have a frost after the spring date, so give tender crops (tomatoes, peppers, squash) some slack.
| Crop | Start indoors | Spring planting | Fall planting |
|---|---|---|---|
| Tomato | Mar 9–23 | May 11–25 (transplant) | – |
| Pepper (sweet and hot) | Feb 23–Mar 9 | May 18–Jun 1 (transplant) | – |
| Eggplant | Feb 23–Mar 9 | May 18–Jun 1 (transplant) | – |
| Tomatillo | Mar 9–23 | May 11–25 (transplant) | – |
| Lettuce | Mar 9–23 | Apr 13–May 4 (transplant) Apr 6–May 18 (sow outdoors) | Aug 13–Sep 3 (transplant) Jul 30–Aug 27 (sowing) |
| Spinach | – | Mar 23–Apr 13 (sow outdoors) | Aug 13–Sep 3 (sowing) |
| Kale | Mar 9–23 | Apr 6–20 (transplant) Apr 6–20 (sow outdoors) | Jul 16–Aug 13 (transplant) Jul 2–30 (sowing) |
| Collards | Mar 9–23 | Apr 6–May 4 (transplant) Apr 6–May 4 (sow outdoors) | Jul 16–Aug 13 (transplant) Jul 2–30 (sowing) |
| Broccoli | Feb 23–Mar 9 | Apr 6–20 (transplant) | Jul 2–30 (transplant) |
| Cabbage | Feb 23–Mar 9 | Apr 6–20 (transplant) | Jul 2–30 (transplant) |
| Cauliflower | Feb 23–Mar 9 | Apr 20–May 4 (transplant) | Jul 2–30 (transplant) |
| Brussels sprouts | Feb 9–23 | Apr 6–20 (transplant) | Jun 18–Jul 9 (transplant) |
| Kohlrabi | Mar 9–23 | Apr 6–20 (transplant) Apr 6–20 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Bok choy / Asian greens | – | Apr 6–20 (sow outdoors) | Aug 13–27 (sowing) |
| Arugula | – | Apr 6–May 4 (sow outdoors) | Aug 13–Sep 10 (sowing) |
| Mustard greens | – | Apr 6–27 (sow outdoors) | Aug 13–27 (sowing) |
| Swiss chard | Mar 23–Apr 6 | Apr 20–May 11 (transplant) Apr 20–May 18 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Beet | – | Apr 6–May 4 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Carrot | – | Apr 13–May 11 (sow outdoors) | Jul 16–30 (sowing) |
| Radish | – | Mar 30–May 11 (sow outdoors) | Aug 27–Sep 10 (sowing) |
| Turnip | – | Apr 6–27 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Parsnip | – | Apr 13–May 4 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 9–Apr 6 (sow outdoors) | Jul 16–30 (sowing) |
| Onion (bulbing) | Feb 9–23 | Mar 23–Apr 6 (transplant) | – |
| Green onion / scallion | – | Mar 23–Apr 20 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Leek | Feb 9–23 | Apr 6–20 (transplant) | – |
| Garlic | – | – | Aug 27–Sep 24 (sowing) |
| Shallot | – | Mar 23–Apr 6 (transplant) | Aug 27–Sep 24 (sowing) |
| Potato | – | Apr 6–20 (transplant) | Jun 18–Jul 2 (transplant) |
| Sweet potato | – | May 25–Jun 8 (transplant) | – |
| Sweet corn | – | May 11–25 (sow outdoors) | – |
| Bean, bush (snap) | – | May 11–25 (sow outdoors) | – |
| Bean, pole | – | May 11–25 (sow outdoors) | – |
| Lima bean | – | May 18–Jun 1 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 25–Jun 15 (sow outdoors) | – |
| Cucumber | Apr 6–13 | May 11–25 (transplant) May 11–25 (sow outdoors) | – |
| Summer squash / zucchini | Apr 6–13 | May 11–25 (transplant) May 11–25 (sow outdoors) | – |
| Winter squash | Apr 6–13 | May 11–25 (transplant) May 11–25 (sow outdoors) | – |
| Pumpkin | – | May 11–25 (sow outdoors) | – |
| Watermelon | Apr 6–13 | May 18–Jun 1 (transplant) May 18–Jun 1 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 6–13 | May 18–Jun 1 (transplant) May 18–Jun 1 (sow outdoors) | – |
| Okra | Mar 23–Apr 6 | May 18–Jun 1 (transplant) May 18–Jun 1 (sow outdoors) | – |
| Celery | Feb 9–23 | May 11–18 (transplant) | – |
| Basil | Mar 23–Apr 6 | May 11–25 (transplant) May 11–25 (sow outdoors) | – |
| Cilantro | – | Apr 20–May 18 (sow outdoors) | Aug 13–27 (sowing) |
| Parsley | Feb 23–Mar 9 | Apr 20–May 4 (transplant) Apr 13–May 4 (sow outdoors) | – |
| Dill | – | May 4–18 (sow outdoors) | Aug 13–27 (sowing) |
| Sunflower | – | May 4–18 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 6–20 (transplant) | – |
| Rhubarb (crowns) | – | Apr 6–20 (transplant) | – |
| Strawberry (plants) | – | Apr 6–20 (transplant) | Jul 30–Aug 27 (transplant) |
Typical ranges from university extension planting calendars, adjusted to your frost dates. Probabilities, not guarantees. Fall windows that would overlap spring planting are left out, as are fall crops of frost-tender plants where the frost-free season is under 210 days.
Where these numbers come from
Station: Greenland, NH (NOAA GHCN-Daily ID USC00273626), elevation 95 ft, 3.9 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Durham 2 SSW, NH | 8 mi | May 7 | Oct 4 |
| Durham, NH | 9 mi | May 8 | Oct 4 |
| Durham 2 N, NH | 9 mi | May 3 | Oct 10 |
The average last-frost dates of these stations span 5 days, a rough guide to local variation. See data sources & methods.
Frost questions for 03801
When is the last frost in 03801?
The average (50% chance) last spring freeze of 32°F for ZIP 03801 is May 4. For a more cautious planting date, use May 18, when only 1 year in 10 still sees a later freeze.
When is the first frost in 03801?
The average first fall freeze is October 8. In 1 year in 10 it comes by September 27.
What hardiness zone is 03801?
ZIP 03801 is in USDA zone 6a (-10 to -5°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 03801 right now?
This page shows the latest 2-inch and 4-inch soil temperature from the nearest public soil station (USDA SCAN, NOAA USCRN or TexMesonet), or a labeled estimate when no station is close, against the 50–55°F spring pre-emergent band.
Nearby ZIP codes
03840 03904 Kittery 03870 03854 03903 South Eliot 03885 03824 Durham 03871
Other ZIP codes in Rockingham County
03032 03034 03036 03037 03038 03042 03044 03053 03077 03079 03087 03261 03290 03291 03811 03819 03826 03827 03833 03840 03841 03842 03844 03848 All Rockingham County frost dates · New Hampshire frost dates
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