Frost dates for 06401Ansonia, CT
The average last spring frost in Ansonia is April 25 and the average first fall frost is October 17, giving a typical growing season of about 175 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 25
- Average first fall frost
- Oct 17
- Growing season
- 175 days
Safer after May 10 (1-in-10 risk)
Possible by Oct 4 (1-in-10 risk)
Last frost typically in 175 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Apr 24 · May 8 · May 22 | Sep 27 · Oct 7 · Oct 21 | 151 days | 100% |
| Frost / freeze (32°F) | Apr 11 · Apr 25 · May 10 | Oct 4 · Oct 17 · Nov 1 | 175 days | 100% |
| Hard freeze (28°F) | Mar 30 · Apr 10 · Apr 27 | Oct 14 · Oct 30 · Nov 13 | 202 days | 100% |
Planting calendar for Ansonia
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Mar 25 – May 31 |
| Tomatoes | Transplant outdoors | May 11 – Jun 27 |
| Peppers | Start seeds indoors | Mar 25 – Apr 25 |
| Peppers | Transplant outdoors | May 25 – Jun 25 |
| Eggplant | Start seeds indoors | Apr 11 – May 10 |
| Eggplant | Transplant outdoors | May 25 – Jun 25 |
| Cucumbers | Sow outdoors | May 25 – Jul 7 |
| Summer squash | Sow outdoors | May 11 – Jun 25 |
| Winter squash & pumpkins | Sow outdoors | May 25 – Jun 25 |
| Snap beans | Sow outdoors | May 11 – Jul 30 |
| Sweet corn | Sow outdoors | May 11 – Jun 27 |
| Watermelon & cantaloupe | Sow outdoors | May 25 – Jun 25 |
| Okra | Sow outdoors | May 18 – Jun 10 |
| Peas | Sow outdoors (spring) | Mar 25 – May 10 |
| Potatoes | Plant outdoors (spring) | Mar 25 – May 25 |
| Onions | Start seeds indoors (spring) | Feb 11 – Mar 10 |
| Onions | Transplant outdoors (spring) | Apr 11 – May 10 |
| Broccoli | Start seeds indoors (spring) | Mar 7 – Apr 10 |
| Broccoli | Transplant outdoors (spring) | Apr 11 – May 10 |
| Broccoli | Start seeds indoors (fall) | Jun 17 – Jun 27 |
| Broccoli | Transplant outdoors (fall) | Jul 17 – Jul 28 |
| Cabbage | Start seeds indoors (spring) | Feb 25 – Mar 25 |
| Cabbage | Transplant outdoors (spring) | Mar 25 – Apr 25 |
| Cabbage | Start seeds indoors (fall) | Jun 7 – Jul 7 |
| Cabbage | Transplant outdoors (fall) | Jul 7 – Aug 7 |
| Leaf lettuce | Sow outdoors (spring) | Mar 25 – Jun 10 |
| Leaf lettuce | Sow outdoors (fall) | Jul 7 – Aug 23 |
| Spinach | Sow outdoors (spring) | Mar 18 – May 1 |
| Spinach | Sow outdoors (fall) | Jul 24 – Aug 28 |
| Radishes | Sow outdoors (spring) | Mar 25 – May 15 |
| Radishes | Sow outdoors (fall) | Jul 7 – Sep 7 |
| Kale | Sow outdoors (spring) | Apr 11 – May 1 |
| Kale | Sow outdoors (fall) | Jun 30 – Aug 7 |
| Carrots | Sow outdoors (spring) | Apr 25 – Jun 10 |
| Carrots | Sow outdoors (fall) | Jun 7 – Jul 23 |
| Garlic | Plant outdoors (fall) | Oct 7 – Nov 7 |
Where these dates come from
ZIP code 06401 is matched to the NOAA station Ansonia 1 Ne, CT, 1.6 km away, at 136 ft elevation (38 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ansonia 1 Ne, CT (used) | 136 ft | Apr 25 | Oct 17 |
| Mt Carmel, CT | 180 ft | Apr 18 | Oct 26 |
| New Haven Tweed Ap, CT | 3 ft | Apr 17 | Oct 27 |
| Bridgeport Sikorsky Mem Ap, CT | 5 ft | Apr 5 | Nov 6 |
Frost dates near Ansonia
- Derby, CT 06418 · last Apr 25, first Oct 17
- Seymour, CT 06483 · last Apr 25, first Oct 17
- Shelton, CT 06484 · last Apr 20, first Oct 20
- Orange, CT 06477 · last Apr 17, first Oct 27
- New Haven, CT 06515 · last Apr 17, first Oct 27
- Oxford, CT 06478 · last Apr 20, first Oct 20
- Beacon Falls, CT 06403 · last Apr 26, first Oct 16
- Stevenson, CT 06491 · last Apr 25, first Oct 17
Frequently asked questions
- When is the last frost in Ansonia, CT?
- For ZIP code 06401, the average last spring frost (32°F) is April 25, based on NOAA 1991-2020 climate normals for the Ansonia 1 Ne, CT weather station. There is a 1-in-10 chance of a frost after May 10.
- When is the first frost in Ansonia, CT?
- The average first fall frost (32°F) is October 17. There is a 1-in-10 chance of frost by October 4, so tender plants are at risk from that point on.
- How long is the growing season in 06401?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 175 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.