Frost dates for New Haven, Connecticut
In New Haven, half of springs have had their last frost by April 17 (and 1 spring in 10 still has one after May 1), and half of falls have had their first frost by October 27, leaving about 193 frost-free days in a typical year. Here is how sure those dates are, what they mean for planting, and where they come from.
Frost dates for
New Haven, Connecticut
Last spring frost
April 17
Half of springs have their last frost by this date. For a safer bet, wait until May 1: only 1 spring in 10 has a frost after that.
First fall frost
October 27
Half of falls have their first frost by this date. In 1 fall in 10 it comes by October 11.
Growing season
193 days
Frost-free days in a typical year. 9 years in 10 get at least 174.
Hardiness zone
7a
2023 USDA map: the coldest night of winter averages 0°F to 5°F. It was 7a on the 2012 map too. ZIP codes within about 6 miles of the city's center: 3 in 6b and 9 in 7a.
Print a year planner for New Haven
Frost risk through the year
How sure are these dates?
A frost date is a probability, not a promise. NOAA worked out, from 30 years of nightly lows, how often the last spring frost and the first fall frost fall on each date. The middle column is the typical year. The outer columns are the early and late years that come about once a decade.
| Early year 1 in 10 | Typical year 1 in 2 | Late year 1 in 10 | |
|---|---|---|---|
| Last frost in spring | April 2 | April 17 | May 1 |
| First frost in fall | October 11 | October 27 | November 8 |
The frost-free season between them runs 193 days in a typical year. In 1 year in 10 it is 211 days or longer, and in 1 year in 10 it is 174 days or shorter.
- Hard freeze (28°F): typically last on April 4 and first on November 6. It is a harder freeze than the 32°F frost line, cold enough to damage many garden plants; how hardy a crop is decides whether it comes through. (The National Weather Service's own hard-freeze threshold varies from office to office.)
- Frost possible (36°F at the station): typically last on April 30 and first on October 15. On clear, still nights the ground can be several degrees colder than the thermometer, so frost can form on plants when the official reading is in the mid-30s.
In 8 springs out of 10, the last frost in New Haven comes between April 2 and May 1, a window of 29 days. That is about average for NOAA's stations (the typical window is 31 days).
Among Connecticut's 23 NOAA stations with a frost every year, 70 percent have their typical last frost later than New Haven does.
Planting calendar for New Haven
These dates count from the typical last and first frosts, using the planting rules published by Colorado State University Extension (spring), Virginia Cooperative Extension (fall crops) and University of Minnesota Extension (garlic, where winters are hard). Weather in any one year can run early or late, so check the forecast before you plant tender crops.
| When | What to do | Why then |
|---|---|---|
| January | ||
| January 30 to February 27 | Broccoli and cabbage Start seeds indoors | 5 to 7 weeks before planting them out |
| February | ||
| February 13 to March 13 | Cauliflower Start seeds indoors | 5 to 7 weeks before planting out |
| February 27 to March 20 | Eggplant Start seeds indoors | 6 to 9 weeks before planting out |
| March | ||
| March 6 to 20 | Peppers Start seeds indoors | 6 to 8 weeks before planting out |
| March 13 to 27 | Tomatoes Start seeds indoors | 5 to 7 weeks before planting out |
| March 20 to April 3 | Peas, spinach, lettuce, radishes, onion sets, turnips Sow outdoors, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| March 20 to April 3 | Broccoli and cabbage Plant out, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| April | ||
| April 3 to 17 | Beets, carrots, potatoes, Swiss chard Plant outdoors, as early as | semi-hardy crops: up to 2 weeks before the typical last frost |
| April 3 to 17 | Cauliflower Plant out, as early as | semi-hardy: up to 2 weeks before the typical last frost |
| April 17 | Snap beans, sweet corn, cucumbers, summer squash Sow outdoors around | tender crops: around the typical last frost date |
| May | ||
| May 1 | Tomatoes, peppers, eggplant Plant out from | very tender: 2 weeks or more after the typical last frost |
| May 1 | Melons, winter squash, pumpkins, lima beans Sow outdoors from | very tender: 2 weeks or more after the typical last frost |
| June | ||
| June 1 to 15 | Cabbage for fall Start seeds | set the plants out by July 20 |
| June 21 to July 5 | Broccoli for fall Start seeds | set the plants out by August 9 |
| July | ||
| July 31 | Snap beans for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August | ||
| August 4 | Carrots for fall Last date to sow | 70 days to harvest, plus 2 weeks for slower fall growth |
| August 5 | Cucumbers for fall Last date to sow | 55 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August 9 | Peas for fall Last date to sow | 65 days to harvest, plus 2 weeks for slower fall growth |
| August 10 | Summer squash for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August 14 | Leaf lettuce and beets for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth |
| August 24 | Turnips and kohlrabi for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth |
| September | ||
| September 3 | Spinach for fall Last date to sow | 40 days to harvest, plus 2 weeks for slower fall growth |
| September 13 | Radishes for fall Last date to sow | 30 days to harvest, plus 2 weeks for slower fall growth |
| October | ||
| October 11 | Tomatoes, peppers, squash, melons, cucumbers Watch the forecast from | in 1 fall in 10 the first frost comes by this date; pick tender crops before a frost |
| November | ||
| November 13 to 20 | Garlic Plant cloves | one or two weeks after the typical first hard freeze (28°F), our reading of the first killing frost |
Want more insurance? Shift every spring date 14 days later. That plans around May 1, the date after which only 1 spring in 10 has a frost.
For spring bulbs such as tulips and daffodils, plant once the soil has cooled to about 50 to 55°F and keep going until a couple of weeks before the ground freezes. Our guide to fall planting explains how to tell.
Where these numbers come from
These dates come from NOAA's weather station New Haven Tweed Airport (station USW00014758), 4 miles from the center of New Haven. It sits at about the same elevation, at sea level. NOAA rates this station's record as representative: at least 10 of the 30 years, with the gaps filled from nearby stations.
The same station also gives the frost dates for West Haven, Ansonia and Derby.
Our ZIP code lookup matches these 9 ZIP codes to the same station, so they get the same dates: 06405, 06413, 06498, 06510, 06511, 06512, 06513, 06516, 06519. Hardiness zones are worked out separately for each ZIP code.
Nearby places
- Bridgeport, Connecticut: last frost around April 5, first frost around November 6 (15 miles away)
- Waterbury, Connecticut: last frost around April 26, first frost around October 16 (20 miles away)
- Hartford, Connecticut: last frost around April 17, first frost around October 26 (35 miles away)
See frost dates across Connecticut, or look up your own ZIP code for the station nearest you. Want the background? Read what a last frost date really means.