USDA Hardiness Zone 6b
Frost Dates for 06473 — North Haven, Connecticut
NOAA 1991–2020 normals from Mt Carmel, CT (180 ft), 3 miles northwest.
Updated
In North Haven, the last spring frost (32°F) is around April 18 in half of years and has passed by May 3 in nine years out of ten. The first fall frost comes around October 26, as early as October 11 one year in ten, leaving a typical freeze-free season of 191 days (NOAA, Mt Carmel, CT).
- Last spring frost
- April 18
- First fall frost
- October 26
- Growing season
- 191 days
- Hardiness zone
- 6b
50% probability
50% probability
freeze-free, 50%
-5 to 0°F (-20.6 to -17.8°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 North Haven
Half of springs at Mt Carmel, CT see their last 32°F night by April 18; only one in ten is past it by April 5, and one in ten still has one after May 3. Planting tender crops after April 23 leaves a 30% risk of a frost on them, after April 28 20%, and after May 3 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 50% of the 28 Connecticut stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 26 in half of years, as early as October 11 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 11 days later, around November 6; in spring the one-in-ten date for 28°F is April 19, 14 days before the 32°F one. The freeze-free season lasts 191 days in a typical year, longer than at 68% of the 28 Connecticut stations; it reaches 208 days one year in ten and falls short of 172 one year in ten. On average 123 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 May 1, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 16 and March 7.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 18 | Apr 22 | Apr 25 | Apr 28 | May 1 | May 3 | May 6 | May 10 | May 16 |
| 32°F | Apr 5 | Apr 9 | Apr 12 | Apr 15 | Apr 18 | Apr 20 | Apr 23 | Apr 28 | May 3 |
| 28°F | Mar 23 | Mar 29 | Mar 31 | Apr 2 | Apr 5 | Apr 7 | Apr 10 | Apr 13 | Apr 19 |
| 24°F | Mar 11 | Mar 16 | Mar 19 | Mar 23 | Mar 26 | Mar 29 | Mar 31 | Apr 2 | Apr 6 |
| 20°F | Mar 2 | Mar 7 | Mar 10 | Mar 14 | Mar 16 | Mar 19 | Mar 23 | Mar 27 | Mar 30 |
| 16°F | Feb 14 | Feb 22 | Feb 28 | Mar 3 | Mar 7 | Mar 10 | Mar 13 | Mar 17 | Mar 23 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 2 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 18 | Oct 21 | Oct 25 | Oct 30 |
| 32°F | Oct 11 | Oct 16 | Oct 20 | Oct 23 | Oct 26 | Oct 29 | Nov 1 | Nov 4 | Nov 9 |
| 28°F | Oct 22 | Oct 27 | Oct 31 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 22 |
| 24°F | Nov 2 | Nov 7 | Nov 12 | Nov 15 | Nov 19 | Nov 23 | Nov 27 | Dec 1 | Dec 6 |
| 20°F | Nov 16 | Nov 22 | Nov 26 | Nov 30 | Dec 2 | Dec 5 | Dec 9 | Dec 14 | Dec 21 |
| 16°F | Nov 30 | Dec 4 | Dec 7 | Dec 11 | Dec 16 | Dec 20 | Dec 24 | Dec 29 | Jan 4 |
Freeze probabilities 1991–2020 at Mt Carmel, 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 06473 →Compare North Haven with another place →
Weather by month in North Haven
July is the warmest month at Mt Carmel, CT, averaging 85°F by day and 64°F at night; January is the coldest at 38°F and 20°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 15% of years.
Warmth for growing adds up to 3,078 growing degree days a year (base 50°F), more than at 79% of the 28 Connecticut stations. 31% of them (949) have built up by the end of June, and July adds the most, 752. Precipitation totals 50.5 inches a year, most in June (4.9") and least in February (3.5"); May to September bring 41% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 38 | 20 | 3.6 | 100% | 27 | 1 |
| Feb | 41 | 22 | 3.5 | 100% | 24 | 1 |
| Mar | 48 | 28 | 4.4 | 100% | 22 | 9 |
| Apr | 61 | 38 | 4.7 | 97% | 6 | 82 |
| May | 71 | 48 | 3.7 | 15% | <1 | 299 |
| Jun | 79 | 58 | 4.9 | 0% | 0 | 557 |
| Jul | 85 | 64 | 3.8 | 0% | 0 | 752 |
| Aug | 84 | 62 | 3.8 | 0% | 0 | 707 |
| Sep | 76 | 55 | 4.3 | 0% | 0 | 472 |
| Oct | 64 | 43 | 4.9 | 65% | 4 | 167 |
| Nov | 53 | 34 | 4.4 | 100% | 16 | 28 |
| Dec | 42 | 27 | 4.5 | 100% | 24 | 4 |
Monthly normals 1991–2020 at Mt Carmel, CT (180 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, New Haven Tweed Airport, CT, 8 miles south of North Haven and 177 feet lower, has a last frost 1 day earlier (April 17), a first frost 1 day later (October 27), a season 2 days longer.
When it snows in North Haven, Connecticut
The first measurable snow (0.1 inch or more) in North 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, 3 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 28 days after the last snow.
Planting calendar for 06473
| When | What to do |
|---|---|
| February 7 – February 21 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 21 – March 7 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 21 – April 4 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 18 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 3 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 12 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 26 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 06473 is 3 miles from Mt Carmel, CT, which stands at 180 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station; its figures are presented in full for 06770 (Naugatuck). The 2023 USDA Plant Hardiness Zone Map lists ZIP 06473 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°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.