Frost dates for ZIP 03230 (Merrimack County, 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, Grafton, NH (5 miles away).
- Average last spring frostMay 2150% chance of a 32°F freeze after this date
- Average first fall frostSep 2650% chance of a 32°F freeze by this date
- Growing season (frost-free)127 daysmedian, 32°F threshold
- USDA hardiness zone5a-20 to -15°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
49°F Below 50°F
24-hour average · latest 47°F, as of Oct 17, 10:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Hubbard Brook (30 mi), Durham 2 N (53 mi), Durham 2 SSW (54 mi).
4-inch depth
50°F 50–55°F
24-hour average · latest 50°F, as of Oct 17, 10:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Hubbard Brook (30 mi), Durham 2 N (53 mi), Durham 2 SSW (54 mi).
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 03230 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 50°F at 4 inches (estimated soil temperature, not a station reading). 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) | May 7 |
| 50% (the "average" last frost) | May 21 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 5 |
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 12 |
| 50% (the "average" first frost) | Sep 26 |
| 90% (late: most years have frozen by now) | Oct 7 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Jun 2 | Sep 14 |
| 32°F (freeze) | May 21 | Sep 26 |
| 28°F (hard freeze) | May 8 | Oct 5 |
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 03230
Dates count from your average last spring frost (May 21) and first fall frost (Sep 26). 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 26–Apr 9 | May 28–Jun 11 (transplant) | – |
| Pepper (sweet and hot) | Mar 12–26 | Jun 4–18 (transplant) | – |
| Eggplant | Mar 12–26 | Jun 4–18 (transplant) | – |
| Tomatillo | Mar 26–Apr 9 | May 28–Jun 11 (transplant) | – |
| Lettuce | Mar 26–Apr 9 | Apr 30–May 21 (transplant) Apr 23–Jun 4 (sow outdoors) | Aug 1–22 (transplant) Jul 18–Aug 15 (sowing) |
| Spinach | – | Apr 9–30 (sow outdoors) | Aug 1–22 (sowing) |
| Kale | Mar 26–Apr 9 | Apr 23–May 7 (transplant) Apr 23–May 7 (sow outdoors) | Jul 4–Aug 1 (transplant) Jun 20–Jul 18 (sowing) |
| Collards | Mar 26–Apr 9 | Apr 23–May 21 (transplant) Apr 23–May 21 (sow outdoors) | Jul 4–Aug 1 (transplant) Jun 20–Jul 18 (sowing) |
| Broccoli | Mar 12–26 | Apr 23–May 7 (transplant) | Jun 20–Jul 18 (transplant) |
| Cabbage | Mar 12–26 | Apr 23–May 7 (transplant) | Jun 20–Jul 18 (transplant) |
| Cauliflower | Mar 12–26 | May 7–21 (transplant) | Jun 20–Jul 18 (transplant) |
| Brussels sprouts | Feb 26–Mar 12 | Apr 23–May 7 (transplant) | Jun 6–27 (transplant) |
| Kohlrabi | Mar 26–Apr 9 | Apr 23–May 7 (transplant) Apr 23–May 7 (sow outdoors) | Jul 18–Aug 1 (sowing) |
| Bok choy / Asian greens | – | Apr 23–May 7 (sow outdoors) | Aug 1–15 (sowing) |
| Arugula | – | Apr 23–May 21 (sow outdoors) | Aug 1–29 (sowing) |
| Mustard greens | – | Apr 23–May 14 (sow outdoors) | Aug 1–15 (sowing) |
| Swiss chard | Apr 9–23 | May 7–28 (transplant) May 7–Jun 4 (sow outdoors) | Jul 18–Aug 1 (sowing) |
| Beet | – | Apr 23–May 21 (sow outdoors) | Jul 18–Aug 1 (sowing) |
| Carrot | – | Apr 30–May 28 (sow outdoors) | Jul 4–18 (sowing) |
| Radish | – | Apr 16–May 28 (sow outdoors) | Aug 15–29 (sowing) |
| Turnip | – | Apr 23–May 14 (sow outdoors) | Jul 18–Aug 1 (sowing) |
| Parsnip | – | Apr 30–May 21 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 26–Apr 23 (sow outdoors) | Jul 4–18 (sowing) |
| Onion (bulbing) | Feb 26–Mar 12 | Apr 9–23 (transplant) | – |
| Green onion / scallion | – | Apr 9–May 7 (sow outdoors) | Jul 18–Aug 1 (sowing) |
| Leek | Feb 26–Mar 12 | Apr 23–May 7 (transplant) | – |
| Garlic | – | – | Aug 15–Sep 12 (sowing) |
| Shallot | – | Apr 9–23 (transplant) | Aug 15–Sep 12 (sowing) |
| Potato | – | Apr 23–May 7 (transplant) | Jun 6–20 (transplant) |
| Sweet potato | – | Jun 11–25 (transplant) | – |
| Sweet corn | – | May 28–Jun 11 (sow outdoors) | – |
| Bean, bush (snap) | – | May 28–Jun 11 (sow outdoors) | – |
| Bean, pole | – | May 28–Jun 11 (sow outdoors) | – |
| Lima bean | – | Jun 4–18 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 11–Jul 2 (sow outdoors) | – |
| Cucumber | Apr 23–30 | May 28–Jun 11 (transplant) May 28–Jun 11 (sow outdoors) | – |
| Summer squash / zucchini | Apr 23–30 | May 28–Jun 11 (transplant) May 28–Jun 11 (sow outdoors) | – |
| Winter squash | Apr 23–30 | May 28–Jun 11 (transplant) May 28–Jun 11 (sow outdoors) | – |
| Pumpkin | – | May 28–Jun 11 (sow outdoors) | – |
| Watermelon | Apr 23–30 | Jun 4–18 (transplant) Jun 4–18 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 23–30 | Jun 4–18 (transplant) Jun 4–18 (sow outdoors) | – |
| Okra | Apr 9–23 | Jun 4–18 (transplant) Jun 4–18 (sow outdoors) | – |
| Celery | Feb 26–Mar 12 | May 28–Jun 4 (transplant) | – |
| Basil | Apr 9–23 | May 28–Jun 11 (transplant) May 28–Jun 11 (sow outdoors) | – |
| Cilantro | – | May 7–Jun 4 (sow outdoors) | Aug 1–15 (sowing) |
| Parsley | Mar 12–26 | May 7–21 (transplant) Apr 30–May 21 (sow outdoors) | – |
| Dill | – | May 21–Jun 4 (sow outdoors) | Aug 1–15 (sowing) |
| Sunflower | – | May 21–Jun 4 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 23–May 7 (transplant) | – |
| Rhubarb (crowns) | – | Apr 23–May 7 (transplant) | – |
| Strawberry (plants) | – | Apr 23–May 7 (transplant) | Jul 18–Aug 15 (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: Grafton, NH (NOAA GHCN-Daily ID USC00273530), elevation 830 ft, 5.0 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Franklin Falls Dam, NH | 11 mi | May 7 | Oct 3 |
| Salisbury, NH | 14 mi | May 14 | Sep 29 |
| Mt Sunapee, NH | 17 mi | May 2 | Oct 9 |
The average last-frost dates of these stations span 19 days, a rough guide to local variation. See data sources & methods.
Frost questions for 03230
When is the last frost in 03230?
The average (50% chance) last spring freeze of 32°F for ZIP 03230 is May 21. For a more cautious planting date, use June 5, when only 1 year in 10 still sees a later freeze.
When is the first frost in 03230?
The average first fall freeze is September 26. In 1 year in 10 it comes by September 12.
What hardiness zone is 03230?
ZIP 03230 is in USDA zone 5a (-20 to -15°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 03230 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
03243 03240 03216 03287 03231 03233 03284 03222 Bristol
Other ZIP codes in Merrimack County
03046 03106 03216 03221 03224 03229 03231 03233 03234 03235 03242 03243 03255 03257 03258 03260 03263 03268 03273 03275 03276 03278 03287 03301 All Merrimack County frost dates · New Hampshire frost dates
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