USDA Hardiness Zone 7a
Frost Dates for 06513 — New Haven, Connecticut
NOAA 1991–2020 normals from New Haven Tweed Airport, CT (3 ft), 4 miles south.
Updated
In New Haven, the last spring frost (32°F) is around April 17 in half of years and has passed by May 1 in nine years out of ten. The first fall frost comes around October 27, as early as October 11 one year in ten, leaving a typical freeze-free season of 193 days (NOAA, New Haven Tweed Airport, CT).
- Last spring frost
- April 17
- First fall frost
- October 27
- Growing season
- 193 days
- Hardiness zone
- 7a
50% probability
50% probability
freeze-free, 50%
0 to 5°F (-17.8 to -15.0°C) coldest night
- First snow
- December 8
- Last snow
- March 21
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
24 of 24 observed
NOAA normal
Frost risk by date in New Haven
Half of springs at New Haven Tweed Airport, CT see their last 32°F night by April 17; only one in ten is past it by April 2, and one in ten still has one after May 1. Planting tender crops after April 22 leaves a 30% risk of a frost on them, after April 26 20%, and after May 1 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 54% of the 28 Connecticut stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 27 in half of years, as early as October 11 one year in ten, and holds off past November 8 one year in ten. A hard freeze of 28°F follows 10 days later, around November 6; in spring the one-in-ten date for 28°F is April 18, 13 days before the 32°F one. The freeze-free season lasts 193 days in a typical year, longer than at 79% of the 28 Connecticut stations; it reaches 211 days one year in ten and falls short of 174 one year in ten. On average 102 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 13 days longer, to about April 30, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 20 and March 2.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 17 | Apr 21 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 4 | May 7 | May 12 |
| 32°F | Apr 2 | Apr 8 | Apr 11 | Apr 15 | Apr 17 | Apr 20 | Apr 22 | Apr 26 | May 1 |
| 28°F | Mar 22 | Mar 28 | Mar 31 | Apr 2 | Apr 4 | Apr 6 | Apr 9 | Apr 13 | Apr 18 |
| 24°F | Mar 7 | Mar 13 | Mar 17 | Mar 20 | Mar 25 | Mar 28 | Mar 31 | Apr 2 | Apr 5 |
| 20°F | Feb 24 | Mar 1 | Mar 6 | Mar 10 | Mar 13 | Mar 16 | Mar 19 | Mar 25 | Mar 30 |
| 16°F | Feb 9 | Feb 17 | Feb 23 | Feb 27 | Mar 2 | Mar 6 | Mar 10 | Mar 14 | Mar 22 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 4 | Oct 6 | Oct 9 | Oct 13 | Oct 15 | Oct 18 | Oct 22 | Oct 26 | Nov 1 |
| 32°F | Oct 11 | Oct 16 | Oct 20 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 8 |
| 28°F | Oct 22 | Oct 28 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 21 |
| 24°F | Nov 1 | Nov 7 | Nov 12 | Nov 15 | Nov 19 | Nov 23 | Nov 27 | Dec 1 | Dec 6 |
| 20°F | Nov 15 | Nov 22 | Nov 27 | Dec 1 | Dec 4 | Dec 8 | Dec 12 | Dec 17 | Dec 24 |
| 16°F | Dec 1 | Dec 7 | Dec 11 | Dec 16 | Dec 20 | Dec 23 | Dec 28 | Jan 2 | Jan 10 |
Freeze probabilities 1991–2020 at New Haven Tweed Airport, CT, 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 06513 →Compare New Haven with another place →
Weather by month in New Haven
July is the warmest month at New Haven Tweed Airport, CT, averaging 82°F by day and 66°F at night; January is the coldest at 38°F and 23°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 11% of years.
Warmth for growing adds up to 3,028 growing degree days a year (base 50°F), more than at 68% of the 28 Connecticut stations. 29% of them (878) have built up by the end of June, and July adds the most, 741. Precipitation totals 41.8 inches a year, most in April (4.2") and least in January (2.7"); May to September bring 43% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 38 | 23 | 2.7 | 100% | 25 | 0 |
| Feb | 40 | 24 | 2.8 | 100% | 23 | 0 |
| Mar | 47 | 30 | 3.7 | 100% | 17 | 7 |
| Apr | 58 | 39 | 4.2 | 93% | 4 | 64 |
| May | 68 | 49 | 3.5 | 11% | <1 | 271 |
| Jun | 76 | 59 | 3.5 | 0% | 0 | 536 |
| Jul | 82 | 66 | 3.4 | 0% | 0 | 741 |
| Aug | 81 | 65 | 3.6 | 0% | 0 | 708 |
| Sep | 75 | 57 | 4.0 | 0% | 0 | 480 |
| Oct | 64 | 46 | 3.8 | 64% | 2 | 185 |
| Nov | 53 | 36 | 3.1 | 100% | 10 | 31 |
| Dec | 44 | 29 | 3.5 | 100% | 21 | 4 |
Monthly normals 1991–2020 at New Haven Tweed Airport, CT (3 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Mt Carmel, CT, 6 miles north of New Haven and 177 feet higher, has a last frost 1 day later (April 18), a first frost 1 day earlier (October 26), a season 2 days shorter.
When it snows in New Haven, Connecticut
The first measurable snow (0.1 inch or more) in New Haven usually arrives around December 8, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Mt Carmel, CT, 6.5 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 27 days after the last snow.
Planting calendar for 06513
| When | What to do |
|---|---|
| February 6 – February 20 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 20 – March 6 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 20 – April 3 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 17 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 4 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 13 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 27 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 06513 is 4 miles from New Haven Tweed Airport, CT, which stands at 3 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 10 other ZIP codes share the station; its figures are presented in full for 06516 (West Haven). The 2023 USDA Plant Hardiness Zone Map lists ZIP 06513 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across Connecticut →
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.