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Frost dates for Jefferson, NH

NOAA weather station USC00274329 at 1,235 ft elevation. Based on 10 years within 1991-2020. Last verified 2026-10-17.

Last spring freeze (32°F)

May 8

median: freeze still happened after this date in half of years

May 14 30% risk · May 23 10% risk

First fall freeze (32°F)

Oct 1

median: a freeze had happened by this date in half of years

Sep 16 10% chance of a freeze earlier than this

Freeze-free season

146 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

ThresholdSpring: latest-freeze date at risk of 10% / 30% / 50%Fall: first-freeze date at chance of 10% / 50%
36°F (frost possible)Jun 5 / May 29 / May 22Sep 6 / Sep 19
32°F (freeze)May 23 / May 14 / May 8Sep 16 / Oct 1
28°F (hard freeze)May 10 / May 1 / Apr 27Sep 29 / Oct 16

Also at 32°F, last-freeze 70% date May 3 and 90% date Apr 27 (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 USC00274329, 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.

UNH Extension says that for central New Hampshire, Memorial Day is a conservative estimate of the last frost date (read 2026-10-17).

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.

Last-frost reference date

Showing the schedule for the 2027 season (dates repeat yearly). Table below defaults to Typical; it updates when you choose.

CropStart seeds indoorsOutdoorsUNH Extension rule used
SpinachFeb 19 – Mar 26Set out Apr 2 – Apr 23Start 4-6 wk before set-out; set out 3-6 wk before last frost.
BroccoliMar 5 – Apr 2Set out Apr 16 – Apr 30Start 4-6 wk before set-out; set out 2-4 wk before last frost.
Brussels sproutMar 5 – Apr 2Set out Apr 16 – Apr 30Start 4-6 wk before set-out; set out 2-4 wk before last frost.
CabbageMar 5 – Mar 19Set out Apr 16Start 4-6 wk before set-out; set out 4 wk before last frost.
KaleMar 5 – Mar 19Set out Apr 16Start 4-6 wk before set-out; set out 4 wk before last frost.
KohlrabiMar 5 – Mar 19Set out Apr 16Start 4-6 wk before set-out; set out 4 wk before last frost.
LeekFeb 5 – Feb 19Set out Apr 16Start 8-10 wk before set-out; set out 4 wk before last frost.
LettuceMar 12 – Mar 26Set out Apr 16 – Apr 23Start 4-5 wk before set-out; set out 3-4 wk before last frost.
OnionFeb 5 – Feb 19Set out Apr 16Start 8-10 wk before set-out; set out 4 wk before last frost.
Radish—Sow Apr 16 – Apr 30Sow seed in garden 2-4 wk before last frost.
Turnip—Sow Apr 16 – Apr 30Sow seed in garden 2-4 wk before last frost.
ParsleyFeb 12 – Feb 26Set out Apr 23 – Apr 30Start 9-10 wk before set-out; set out 2-3 wk before last frost.
CauliflowerMar 19 – Apr 2Set out Apr 30Start 4-6 wk before set-out; set out 2 wk before last frost.
Potato—Sow Apr 30 – May 7Plant seed potatoes 1-2 wk before last frost.
Swiss chardMar 19 – Apr 2Set out Apr 30; or sow Apr 16Start 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 May 14Sow seed in garden after last frost.
CeleryFeb 19 – Mar 5Set out on/after May 14Start 10-12 wk before set-out; set out after last frost.
Parsnip—Sow on/after May 14Sow seed in garden after last frost.
CucumberApr 23 – May 7Set out May 21 – May 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 May 21 – May 28Plant slips (young plants) 1-2 wk after last frost.
TomatoMar 26 – Apr 16Set out May 21 – May 28Start 6-8 wk before set-out; set out 1-2 wk after last frost.
BasilApr 2 – Apr 16Set out May 28Start 6-8 wk before set-out; set out 2 wk after last frost.
EggplantMar 19 – Apr 9Set out May 28 – Jun 4Start 8-10 wk before set-out; set out 2-3 wk after last frost.
MelonApr 30 – May 7Set out May 28Start 3-4 wk before set-out; set out 2 wk after last frost.
PepperMar 19 – Apr 2Set out May 28Start 8-10 wk before set-out; set out 2 wk after last frost.
PumpkinApr 30 – May 7Set out May 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 squashApr 30 – May 7Set out May 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 squashApr 30 – May 7Set out May 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.
ZucchiniApr 30 – May 7Set out May 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 15Sow 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 thawsSow seed in garden as soon as soil thaws.

Fall: when the garden ends

At this station the median first 32°F freeze is Oct 1; there is a 10% chance of one before Sep 16. 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 Sep 19 and 10% date Sep 6. UNH Extension notes many fall vegetables tolerate mild frosts down to about 28°F (median first 28°F here: Oct 16), 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 1,235 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