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Frost dates for Groton, CT
NOAA weather station USC00063207 at 40 ft elevation. Based on 24 years within 1991-2020. Last verified 2026-10-17.
Last spring freeze (32°F)
Apr 8
median: freeze still happened after this date in half of years
Apr 14 30% risk · Apr 22 10% risk
First fall freeze (32°F)
Nov 2
median: a freeze had happened by this date in half of years
Oct 18 10% chance of a freeze earlier than this
Freeze-free season
207 days
median length between last spring and first fall 32°F freeze
How to read these dates
Spring: a "10% risk" date means NOAA's 1991-2020 data put the chance of a 32°F or colder night after that date at 10%. The "30% risk" date is the convention used by some popular frost calculators (the Old Farmer's Almanac says it uses a 30% probability threshold, source). Fall: a "10%" date means a 10% chance the first freeze comes before it. Source: NOAA readme.
Full table for this station
| Threshold | Spring: latest-freeze date at risk of 10% / 30% / 50% | Fall: first-freeze date at chance of 10% / 50% |
|---|---|---|
| 36°F (frost possible) | May 5 / Apr 29 / Apr 22 | Oct 8 / Oct 21 |
| 32°F (freeze) | Apr 22 / Apr 14 / Apr 8 | Oct 18 / Nov 2 |
| 28°F (hard freeze) | Apr 7 / Apr 2 / Mar 29 | Nov 1 / Nov 14 |
Also at 32°F, last-freeze 70% date Apr 3 and 90% date Mar 28 (frost still likely after these early dates). Data quality: Representative: 10+ years of qualifying data, missing months filled from nearby stations. Source: NOAA NCEI U.S. Climate Normals 1991-2020, station USC00063207, read 2026-10-17.
Is Memorial Day safe here?
Many New England gardeners wait for Memorial Day (it falls between May 25 and May 31). At this station, NOAA's chance of a 32°F or colder night after May 25 is under 10%, and after May 31 is under 10%. Your own spot may differ. See all stations.
Your planting schedule
Pick how cautious you want to be. The dates apply UNH Extension's per-crop rules (UNH fact sheet, read 2026-10-17) to this station's last-freeze date. UNH's sheet does not say which probability its "last frost" means, so you choose. These are planning dates, not instructions; follow your seed packet and the weather.
Showing the schedule for the 2027 season (dates repeat yearly). Table below defaults to Typical; it updates when you choose.
| Crop | Start seeds indoors | Outdoors | UNH Extension rule used |
|---|---|---|---|
| Spinach | Jan 20 – Feb 24 | Set out Mar 3 – Mar 24 | Start 4-6 wk before set-out; set out 3-6 wk before last frost. |
| Broccoli | Feb 3 – Mar 3 | Set out Mar 17 – Mar 31 | Start 4-6 wk before set-out; set out 2-4 wk before last frost. |
| Brussels sprout | Feb 3 – Mar 3 | Set out Mar 17 – Mar 31 | Start 4-6 wk before set-out; set out 2-4 wk before last frost. |
| Cabbage | Feb 3 – Feb 17 | Set out Mar 17 | Start 4-6 wk before set-out; set out 4 wk before last frost. |
| Kale | Feb 3 – Feb 17 | Set out Mar 17 | Start 4-6 wk before set-out; set out 4 wk before last frost. |
| Kohlrabi | Feb 3 – Feb 17 | Set out Mar 17 | Start 4-6 wk before set-out; set out 4 wk before last frost. |
| Leek | Jan 6 – Jan 20 | Set out Mar 17 | Start 8-10 wk before set-out; set out 4 wk before last frost. |
| Lettuce | Feb 10 – Feb 24 | Set out Mar 17 – Mar 24 | Start 4-5 wk before set-out; set out 3-4 wk before last frost. |
| Onion | Jan 6 – Jan 20 | Set out Mar 17 | Start 8-10 wk before set-out; set out 4 wk before last frost. |
| Radish | — | Sow Mar 17 – Mar 31 | Sow seed in garden 2-4 wk before last frost. |
| Turnip | — | Sow Mar 17 – Mar 31 | Sow seed in garden 2-4 wk before last frost. |
| Parsley | Jan 13 – Jan 27 | Set out Mar 24 – Mar 31 | Start 9-10 wk before set-out; set out 2-3 wk before last frost. |
| Cauliflower | Feb 17 – Mar 3 | Set out Mar 31 | Start 4-6 wk before set-out; set out 2 wk before last frost. |
| Potato | — | Sow Mar 31 – Apr 7 | Plant seed potatoes 1-2 wk before last frost. |
| Swiss chard | Feb 17 – Mar 3 | Set out Mar 31; or sow Mar 17 | Start 4-6 wk before set-out; set out 2 wk before last frost; or sow seed 4 wk before last frost. |
| Bean | — | Sow on/after Apr 14 | Sow seed in garden after last frost. |
| Celery | Jan 20 – Feb 3 | Set out on/after Apr 14 | Start 10-12 wk before set-out; set out after last frost. |
| Parsnip | — | Sow on/after Apr 14 | Sow seed in garden after last frost. |
| Cucumber | Mar 24 – Apr 7 | Set out Apr 21 – Apr 28 Direct sow when soil reaches 70°F | Start 3-4 wk before set-out; set out 1-2 wk after last frost; or sow when soil warms to 70°F. |
| Sweet potato | — | Plant slips Apr 21 – Apr 28 | Plant slips (young plants) 1-2 wk after last frost. |
| Tomato | Feb 24 – Mar 17 | Set out Apr 21 – Apr 28 | Start 6-8 wk before set-out; set out 1-2 wk after last frost. |
| Basil | Mar 3 – Mar 17 | Set out Apr 28 | Start 6-8 wk before set-out; set out 2 wk after last frost. |
| Eggplant | Feb 17 – Mar 10 | Set out Apr 28 – May 5 | Start 8-10 wk before set-out; set out 2-3 wk after last frost. |
| Melon | Mar 31 – Apr 7 | Set out Apr 28 | Start 3-4 wk before set-out; set out 2 wk after last frost. |
| Pepper | Feb 17 – Mar 3 | Set out Apr 28 | Start 8-10 wk before set-out; set out 2 wk after last frost. |
| Pumpkin | Mar 31 – Apr 7 | Set out Apr 28 Direct sow when soil reaches 70°F | Start 3-4 wk before set-out; set out 2 wk after last frost; or sow when soil warms to 70°F. |
| Summer squash | Mar 31 – Apr 7 | Set out Apr 28 Direct sow when soil reaches 70°F | Start 3-4 wk before set-out; set out 2 wk after last frost; or sow when soil warms to 70°F. |
| Winter squash | Mar 31 – Apr 7 | Set out Apr 28 Direct sow when soil reaches 70°F | Start 3-4 wk before set-out; set out 2 wk after last frost; or sow when soil warms to 70°F. |
| Zucchini | Mar 31 – Apr 7 | Set out Apr 28 Direct sow when soil reaches 70°F | Start 3-4 wk before set-out; set out 2 wk after last frost; or sow when soil warms to 70°F. |
| Rutabaga | — | Sow Jun 15 – Jul 15 | Sow seed in garden mid-June to mid-July (fixed dates, not tied to frost). |
| Beet | — | Sow when soil reaches 45°F (use a soil thermometer) | Sow seed in garden when soil warms to 45°F. |
| Carrot | — | Sow when soil reaches 60°F (use a soil thermometer) | Sow seed in garden when soil warms to 60°F. |
| Corn | — | Sow when soil reaches 60°F (use a soil thermometer) | Sow seed in garden when soil warms to 60°F. |
| Pea | — | Sow as soon as soil thaws | Sow seed in garden as soon as soil thaws. |
Fall: when the garden ends
At this station the median first 32°F freeze is Nov 2; there is a 10% chance of one before Oct 18. Tender crops (tomatoes, peppers, basil) can be damaged at 33-36°F (Almanac.com notes some plants are damaged in that range); the 36°F first-frost date here is median Oct 21 and 10% date Oct 8. UNH Extension notes many fall vegetables tolerate mild frosts down to about 28°F (median first 28°F here: Nov 14), and that row covers can extend the season. UNH: Fall vegetable gardening, read 2026-10-17.
Your garden is not the weather station
This station sits at 40 ft. UNH Extension says first-freeze dates vary "even between relatively close locations, based on factors such as elevation" (source), and notes that gardeners who keep garden journals can use their own records. Gardeners on Reddit describe the same thing: elevation and cold spots change when they can plant (for example r/vermont). Treat these dates as a starting point.
Nearby stations
- Groton NEw London AP, CT: 2 mi away, 10 ft elevation, median last 32°F freeze Apr 16
- Norwich Public Utility Plt, CT: 12 mi away, 20 ft elevation, median last 32°F freeze Apr 14
- Westerly State AP, RI: 12 mi away, 81 ft elevation, median last 32°F freeze Apr 11
- Kingston 1 W, RI: 27 mi away, 106 ft elevation, median last 32°F freeze May 1
- Kingston, RI: 27 mi away, 117 ft elevation, median last 32°F freeze May 3