Frost dates for 06521New Haven, CT
The average last spring frost in New Haven is April 17 and the average first fall frost is October 27, giving a typical growing season of about 193 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 17
- Average first fall frost
- Oct 27
- Growing season
- 193 days
Safer after May 1 (1-in-10 risk)
Possible by Oct 11 (1-in-10 risk)
Last frost typically in 167 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 17 · Apr 30 · May 12 | Oct 4 · Oct 15 · Nov 1 | 170 days | 100% |
| Frost / freeze (32°F) | Apr 2 · Apr 17 · May 1 | Oct 11 · Oct 27 · Nov 8 | 193 days | 100% |
| Hard freeze (28°F) | Mar 22 · Apr 4 · Apr 18 | Oct 22 · Nov 6 · Nov 21 | 215 days | 100% |
Planting calendar for New Haven
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 17 – May 23 |
| Tomatoes | Transplant outdoors | May 3 – Jul 7 |
| Peppers | Start seeds indoors | Mar 17 – Apr 17 |
| Peppers | Transplant outdoors | May 17 – Jun 17 |
| Eggplant | Start seeds indoors | Apr 3 – May 2 |
| Eggplant | Transplant outdoors | May 17 – Jun 17 |
| Cucumbers | Sow outdoors | May 17 – Jul 17 |
| Summer squash | Sow outdoors | May 3 – Jun 17 |
| Winter squash & pumpkins | Sow outdoors | May 17 – Jun 17 |
| Snap beans | Sow outdoors | May 3 – Aug 9 |
| Sweet corn | Sow outdoors | May 3 – Jul 7 |
| Watermelon & cantaloupe | Sow outdoors | May 17 – Jun 17 |
| Okra | Sow outdoors | May 10 – Jun 2 |
| Peas | Sow outdoors (spring) | Mar 17 – May 2 |
| Potatoes | Plant outdoors (spring) | Mar 17 – May 17 |
| Onions | Start seeds indoors (spring) | Feb 3 – Mar 2 |
| Onions | Transplant outdoors (spring) | Apr 3 – May 2 |
| Broccoli | Start seeds indoors (spring) | Feb 27 – Apr 2 |
| Broccoli | Transplant outdoors (spring) | Apr 3 – May 2 |
| Broccoli | Start seeds indoors (fall) | Jun 27 – Jul 7 |
| Broccoli | Transplant outdoors (fall) | Jul 27 – Aug 7 |
| Cabbage | Start seeds indoors (spring) | Feb 17 – Mar 17 |
| Cabbage | Transplant outdoors (spring) | Mar 17 – Apr 17 |
| Cabbage | Start seeds indoors (fall) | Jun 17 – Jul 17 |
| Cabbage | Transplant outdoors (fall) | Jul 17 – Aug 17 |
| Leaf lettuce | Sow outdoors (spring) | Mar 17 – Jun 2 |
| Leaf lettuce | Sow outdoors (fall) | Jul 17 – Sep 2 |
| Spinach | Sow outdoors (spring) | Mar 10 – Apr 23 |
| Spinach | Sow outdoors (fall) | Aug 3 – Sep 7 |
| Radishes | Sow outdoors (spring) | Mar 17 – May 7 |
| Radishes | Sow outdoors (fall) | Jul 17 – Sep 17 |
| Kale | Sow outdoors (spring) | Apr 3 – Apr 23 |
| Kale | Sow outdoors (fall) | Jul 10 – Aug 17 |
| Carrots | Sow outdoors (spring) | Apr 17 – Jun 2 |
| Carrots | Sow outdoors (fall) | Jun 17 – Aug 2 |
| Garlic | Plant outdoors (fall) | Oct 17 – Nov 17 |
Where these dates come from
ZIP code 06521 is matched to the NOAA station New Haven Tweed Ap, CT, 6 km away, at 3 ft elevation (40 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| New Haven Tweed Ap, CT (used) | 3 ft | Apr 17 | Oct 27 |
| Mt Carmel, CT | 180 ft | Apr 18 | Oct 26 |
| Ansonia 1 Ne, CT | 136 ft | Apr 25 | Oct 17 |
| Bridgeport Sikorsky Mem Ap, CT | 5 ft | Apr 5 | Nov 6 |
Frost dates near New Haven
- New Haven, CT 06501 · last Apr 17, first Oct 27
- Hamden, CT 06517 · last Apr 17, first Oct 27
- West Haven, CT 06516 · last Apr 17, first Oct 27
- Cheshire, CT 06408 · last Apr 17, first Oct 27
- Wallingford, CT 06493 · last Apr 17, first Oct 27
- Orange, CT 06477 · last Apr 17, first Oct 27
- North Haven, CT 06473 · last Apr 17, first Oct 27
- Branford, CT 06405 · last Apr 17, first Oct 27
Frequently asked questions
- When is the last frost in New Haven, CT?
- For ZIP code 06521, the average last spring frost (32°F) is April 17, based on NOAA 1991-2020 climate normals for the New Haven Tweed Ap, CT weather station. There is a 1-in-10 chance of a frost after May 1.
- When is the first frost in New Haven, CT?
- The average first fall frost (32°F) is October 27. There is a 1-in-10 chance of frost by October 11, so tender plants are at risk from that point on.
- How long is the growing season in 06521?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 193 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.