Frost dates for 02109Boston, MA
The average last spring frost in Boston is April 4 and the average first fall frost is November 9, giving a typical growing season of about 218 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 4
- Average first fall frost
- Nov 9
- Growing season
- 218 days
Safer after Apr 17 (1-in-10 risk)
Possible by Oct 29 (1-in-10 risk)
First frost typically in 8 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 6 · Apr 17 · May 1 | Oct 15 · Oct 29 · Nov 11 | 194 days | 100% |
| Frost / freeze (32°F) | Mar 25 · Apr 4 · Apr 17 | Oct 29 · Nov 9 · Nov 22 | 218 days | 100% |
| Hard freeze (28°F) | Mar 15 · Mar 28 · Apr 6 | Nov 8 · Nov 21 · Dec 5 | 239 days | 100% |
Planting calendar for Boston
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 4 – May 10 |
| Tomatoes | Transplant outdoors | Apr 20 – Jul 20 |
| Peppers | Start seeds indoors | Mar 4 – Apr 4 |
| Peppers | Transplant outdoors | May 4 – Jun 4 |
| Eggplant | Start seeds indoors | Mar 21 – Apr 19 |
| Eggplant | Transplant outdoors | May 4 – Jun 4 |
| Cucumbers | Sow outdoors | May 4 – Jul 30 |
| Summer squash | Sow outdoors | Apr 20 – Jun 4 |
| Winter squash & pumpkins | Sow outdoors | May 4 – Jun 4 |
| Snap beans | Sow outdoors | Apr 20 – Aug 22 |
| Sweet corn | Sow outdoors | Apr 20 – Jul 20 |
| Watermelon & cantaloupe | Sow outdoors | May 4 – Jun 4 |
| Okra | Sow outdoors | Apr 27 – May 20 |
| Peas | Sow outdoors (spring) | Mar 4 – Apr 19 |
| Potatoes | Plant outdoors (spring) | Mar 4 – May 4 |
| Onions | Start seeds indoors (spring) | Jan 21 – Feb 17 |
| Onions | Transplant outdoors (spring) | Mar 21 – Apr 19 |
| Broccoli | Start seeds indoors (spring) | Feb 14 – Mar 20 |
| Broccoli | Transplant outdoors (spring) | Mar 21 – Apr 19 |
| Broccoli | Start seeds indoors (fall) | Jul 10 – Jul 20 |
| Broccoli | Transplant outdoors (fall) | Aug 9 – Aug 20 |
| Cabbage | Start seeds indoors (spring) | Feb 4 – Mar 4 |
| Cabbage | Transplant outdoors (spring) | Mar 4 – Apr 4 |
| Cabbage | Start seeds indoors (fall) | Jun 30 – Jul 30 |
| Cabbage | Transplant outdoors (fall) | Jul 30 – Aug 30 |
| Leaf lettuce | Sow outdoors (spring) | Mar 4 – May 20 |
| Leaf lettuce | Sow outdoors (fall) | Jul 30 – Sep 15 |
| Spinach | Sow outdoors (spring) | Feb 25 – Apr 10 |
| Spinach | Sow outdoors (fall) | Aug 16 – Sep 20 |
| Radishes | Sow outdoors (spring) | Mar 4 – Apr 24 |
| Radishes | Sow outdoors (fall) | Jul 30 – Sep 30 |
| Kale | Sow outdoors (spring) | Mar 21 – Apr 10 |
| Kale | Sow outdoors (fall) | Jul 23 – Aug 30 |
| Carrots | Sow outdoors (spring) | Apr 4 – May 20 |
| Carrots | Sow outdoors (fall) | Jun 30 – Aug 15 |
| Garlic | Plant outdoors (fall) | Oct 30 – Nov 30 |
Where these dates come from
ZIP code 02109 is matched to the NOAA station Boston Logan Intl Ap, MA, 3.6 km away, at 12 ft elevation (2 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Boston Logan Intl Ap, MA (used) | 12 ft | Apr 4 | Nov 9 |
| Jamaica Plain, MA | 95 ft | Apr 19 | Oct 23 |
| Blue Hill, MA | 625 ft | Apr 19 | Oct 24 |
| Blue Hill Coop, MA | 625 ft | Apr 18 | Oct 26 |
Frost dates near Boston
- Boston, MA 02117 · last Apr 4, first Nov 9
- Charlestown, MA 02129 · last Apr 4, first Nov 9
- Cambridge, MA 02142 · last Apr 4, first Nov 9
- Chelsea, MA 02150 · last Apr 4, first Nov 9
- Roxbury Crossing, MA 02120 · last Apr 19, first Oct 23
- Somerville, MA 02145 · last Apr 4, first Nov 9
- Roxbury, MA 02119 · last Apr 19, first Oct 23
- Everett, MA 02149 · last Apr 4, first Nov 9
Frequently asked questions
- When is the last frost in Boston, MA?
- For ZIP code 02109, the average last spring frost (32°F) is April 4, based on NOAA 1991-2020 climate normals for the Boston Logan Intl Ap, MA weather station. There is a 1-in-10 chance of a frost after April 17.
- When is the first frost in Boston, MA?
- The average first fall frost (32°F) is November 9. There is a 1-in-10 chance of frost by October 29, so tender plants are at risk from that point on.
- How long is the growing season in 02109?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 218 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.