Frost dates for 01720Acton, MA
The average last spring frost in Acton is May 2 and the average first fall frost is October 6, giving a typical growing season of about 156 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 2
- Average first fall frost
- Oct 6
- Growing season
- 156 days
Safer after May 16 (1-in-10 risk)
Possible by Sep 25 (1-in-10 risk)
Last frost typically in 183 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 30 · May 13 · May 27 | Sep 14 · Sep 27 · Oct 8 | 136 days | 100% |
| Frost / freeze (32°F) | Apr 22 · May 2 · May 16 | Sep 25 · Oct 6 · Oct 22 | 156 days | 100% |
| Hard freeze (28°F) | Apr 8 · Apr 21 · May 5 | Oct 2 · Oct 18 · Nov 3 | 178 days | 100% |
Planting calendar for Acton
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 | Apr 1 – Jun 7 |
| Tomatoes | Transplant outdoors | May 18 – Jun 16 |
| Peppers | Start seeds indoors | Apr 1 – May 2 |
| Peppers | Transplant outdoors | Jun 1 – Jul 2 |
| Eggplant | Start seeds indoors | Apr 18 – May 17 |
| Eggplant | Transplant outdoors | Jun 1 – Jul 2 |
| Cucumbers | Sow outdoors | Jun 1 – Jun 26 |
| Summer squash | Sow outdoors | May 18 – Jul 2 |
| Winter squash & pumpkins | Sow outdoors | Jun 1 – Jul 2 |
| Snap beans | Sow outdoors | May 18 – Jul 19 |
| Sweet corn | Sow outdoors | May 18 – Jun 16 |
| Watermelon & cantaloupe | Sow outdoors | Jun 1 – Jul 2 |
| Okra | Sow outdoors | May 25 – Jun 17 |
| Peas | Sow outdoors (spring) | Apr 1 – May 17 |
| Potatoes | Plant outdoors (spring) | Apr 1 – Jun 1 |
| Onions | Start seeds indoors (spring) | Feb 18 – Mar 17 |
| Onions | Transplant outdoors (spring) | Apr 18 – May 17 |
| Broccoli | Start seeds indoors (spring) | Mar 14 – Apr 17 |
| Broccoli | Transplant outdoors (spring) | Apr 18 – May 17 |
| Broccoli | Start seeds indoors (fall) | Jun 6 – Jun 16 |
| Broccoli | Transplant outdoors (fall) | Jul 6 – Jul 17 |
| Cabbage | Start seeds indoors (spring) | Mar 4 – Apr 1 |
| Cabbage | Transplant outdoors (spring) | Apr 1 – May 2 |
| Cabbage | Start seeds indoors (fall) | May 27 – Jun 26 |
| Cabbage | Transplant outdoors (fall) | Jun 26 – Jul 27 |
| Leaf lettuce | Sow outdoors (spring) | Apr 1 – Jun 17 |
| Leaf lettuce | Sow outdoors (fall) | Jun 26 – Aug 12 |
| Spinach | Sow outdoors (spring) | Mar 25 – May 8 |
| Spinach | Sow outdoors (fall) | Jul 13 – Aug 17 |
| Radishes | Sow outdoors (spring) | Apr 1 – May 22 |
| Radishes | Sow outdoors (fall) | Jun 26 – Aug 27 |
| Kale | Sow outdoors (spring) | Apr 18 – May 8 |
| Kale | Sow outdoors (fall) | Jun 19 – Jul 27 |
| Carrots | Sow outdoors (spring) | May 2 – Jun 17 |
| Carrots | Sow outdoors (fall) | May 27 – Jul 12 |
| Garlic | Plant outdoors (fall) | Sep 26 – Oct 27 |
Where these dates come from
ZIP code 01720 is matched to the NOAA station Maynard 2, MA, 5.1 km away, at 205 ft elevation (18 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Maynard 2, MA (used) | 205 ft | May 2 | Oct 6 |
| Bedford Hanscom Fld, MA | 133 ft | Apr 28 | Oct 10 |
| Bedford, MA | 160 ft | Apr 27 | Oct 13 |
| Lowell, MA | 110 ft | Apr 30 | Oct 10 |
Frost dates near Acton
- Acton, MA 01718 · last May 2, first Oct 6
- Framingham, MA 01703 · last May 2, first Oct 6
- New Town, MA 02456 · last May 2, first Oct 6
- Maynard, MA 01754 · last May 2, first Oct 6
- Boxborough, MA 01719 · last May 2, first Oct 6
- Concord, MA 01742 · last Apr 28, first Oct 10
- Stow, MA 01775 · last May 2, first Oct 6
- Littleton, MA 01460 · last May 2, first Oct 6
Frequently asked questions
- When is the last frost in Acton, MA?
- For ZIP code 01720, the average last spring frost (32°F) is May 2, based on NOAA 1991-2020 climate normals for the Maynard 2, MA weather station. There is a 1-in-10 chance of a frost after May 16.
- When is the first frost in Acton, MA?
- The average first fall frost (32°F) is October 6. There is a 1-in-10 chance of frost by September 25, so tender plants are at risk from that point on.
- How long is the growing season in 01720?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 156 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.