Last spring frost
Apr 21
Frost Dates for Suffield Depot, CT
First fall frost
Oct 16
Growing season
177 days
Hardiness zone
6b
In an average year around Suffield Depot, CT, the last spring frost (32°F) is about Apr 21 and the first fall frost is about Oct 16, giving roughly a 177-day growing season. To be safe most years, wait until Apr 8 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | May 18 | May 5 | Apr 22 |
| Freeze (32°F) | May 6 | Apr 21 | Apr 8 |
| Hard (28°F) | Apr 22 | Apr 7 | Mar 26 |
| Severe (24°F) | Apr 7 | Mar 28 | Mar 14 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 18 | May 14 | May 11 | May 8 | May 5 | May 2 | Apr 30 | Apr 27 | Apr 22 |
| 32°F | May 6 | May 1 | Apr 27 | Apr 24 | Apr 21 | Apr 19 | Apr 16 | Apr 12 | Apr 8 |
| 28°F | Apr 22 | Apr 17 | Apr 13 | Apr 9 | Apr 7 | Apr 4 | Apr 2 | Mar 31 | Mar 26 |
| 24°F | Apr 7 | Apr 3 | Apr 1 | Mar 31 | Mar 28 | Mar 25 | Mar 22 | Mar 19 | Mar 14 |
| 20°F | Mar 31 | Mar 28 | Mar 24 | Mar 21 | Mar 18 | Mar 16 | Mar 13 | Mar 9 | Mar 3 |
| 16°F | Mar 24 | Mar 20 | Mar 17 | Mar 13 | Mar 10 | Mar 7 | Mar 3 | Feb 28 | Feb 23 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Sep 26 | Oct 6 | Oct 21 |
| Freeze (32°F) | Oct 3 | Oct 16 | Nov 2 |
| Hard (28°F) | Oct 13 | Oct 29 | Nov 12 |
| Severe (24°F) | Oct 27 | Nov 11 | Nov 26 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 26 | Sep 30 | Oct 1 | Oct 4 | Oct 6 | Oct 8 | Oct 11 | Oct 15 | Oct 21 |
| 32°F | Oct 3 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 19 | Oct 23 | Oct 27 | Nov 2 |
| 28°F | Oct 13 | Oct 18 | Oct 22 | Oct 26 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 12 |
| 24°F | Oct 27 | Nov 1 | Nov 4 | Nov 7 | Nov 11 | Nov 14 | Nov 17 | Nov 20 | Nov 26 |
| 20°F | Nov 8 | Nov 13 | Nov 17 | Nov 20 | Nov 23 | Nov 26 | Nov 30 | Dec 3 | Dec 9 |
| 16°F | Nov 20 | Nov 26 | Nov 30 | Dec 2 | Dec 5 | Dec 8 | Dec 12 | Dec 17 | Dec 24 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Hartford Bradley Intl Ap, Ct, about 4 miles away@if(!empty($station['elevation_ft'])), at 190 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Suffield Depot, CT?
On average, the last spring frost (32°F) around Suffield Depot, CT is about Apr 21. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 8.
When is the first frost in the fall?
The first fall frost around Suffield Depot, CT typically arrives about Oct 16. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Apr 21 on average, or Apr 8 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 177 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 06078 Planting calendar → Connecticut frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026