Frost dates for 03240Grafton, NH
The average last spring frost in Grafton is May 21 and the average first fall frost is September 26, giving a typical growing season of about 127 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 21
- Average first fall frost
- Sep 26
- Growing season
- 127 days
Safer after Jun 5 (1-in-10 risk)
Possible by Sep 12 (1-in-10 risk)
Last frost typically in 199 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) | May 20 · Jun 2 · Jun 17 | Aug 31 · Sep 14 · Sep 29 | 104 days | 100% |
| Frost / freeze (32°F) | May 7 · May 21 · Jun 5 | Sep 12 · Sep 26 · Oct 7 | 127 days | 100% |
| Hard freeze (28°F) | Apr 26 · May 8 · May 23 | Sep 23 · Oct 5 · Oct 18 | 150 days | 100% |
Planting calendar for Grafton
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 20 – Jun 26 |
| Tomatoes | Transplant outdoors | Jun 6 – Jun 6 |
| Peppers | Start seeds indoors | Apr 20 – May 21 |
| Peppers | Transplant outdoors | Jun 20 – Jul 21 |
| Eggplant | Start seeds indoors | May 7 – Jun 5 |
| Eggplant | Transplant outdoors | Jun 20 – Jul 21 |
| Cucumbers | Sow outdoors | Jun 20 – Jun 16 |
| Summer squash | Sow outdoors | Jun 6 – Jul 21 |
| Winter squash & pumpkins | Sow outdoors | Jun 20 – Jul 21 |
| Snap beans | Sow outdoors | Jun 6 – Jul 9 |
| Sweet corn | Sow outdoors | Jun 6 – Jun 6 |
| Watermelon & cantaloupe | Sow outdoors | Jun 20 – Jul 21 |
| Okra | Sow outdoors | Jun 13 – Jul 6 |
| Peas | Sow outdoors (spring) | Apr 20 – Jun 5 |
| Potatoes | Plant outdoors (spring) | Apr 20 – Jun 20 |
| Onions | Start seeds indoors (spring) | Mar 9 – Apr 5 |
| Onions | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (spring) | Apr 2 – May 6 |
| Broccoli | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (fall) | May 27 – Jun 6 |
| Broccoli | Transplant outdoors (fall) | Jun 26 – Jul 7 |
| Cabbage | Start seeds indoors (spring) | Mar 23 – Apr 20 |
| Cabbage | Transplant outdoors (spring) | Apr 20 – May 21 |
| Cabbage | Start seeds indoors (fall) | May 17 – Jun 16 |
| Cabbage | Transplant outdoors (fall) | Jun 16 – Jul 17 |
| Leaf lettuce | Sow outdoors (spring) | Apr 20 – Jul 6 |
| Leaf lettuce | Sow outdoors (fall) | Jun 16 – Aug 2 |
| Spinach | Sow outdoors (spring) | Apr 13 – May 27 |
| Spinach | Sow outdoors (fall) | Jul 3 – Aug 7 |
| Radishes | Sow outdoors (spring) | Apr 20 – Jun 10 |
| Radishes | Sow outdoors (fall) | Jun 16 – Aug 17 |
| Kale | Sow outdoors (spring) | May 7 – May 27 |
| Kale | Sow outdoors (fall) | Jun 9 – Jul 17 |
| Carrots | Sow outdoors (spring) | May 21 – Jul 6 |
| Carrots | Sow outdoors (fall) | May 17 – Jul 2 |
| Garlic | Plant outdoors (fall) | Sep 16 – Oct 17 |
Where these dates come from
ZIP code 03240 is matched to the NOAA station Grafton, NH, 1.3 km away, at 830 ft elevation (56 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Grafton, NH (used) | 830 ft | May 21 | Sep 26 |
| Franklin Falls Dam, NH | 450 ft | May 7 | Oct 3 |
| Newport, NH | 770 ft | May 14 | Oct 1 |
| Lebanon Muni Ap, NH | 598 ft | May 9 | Oct 6 |
Frost dates near Grafton
- Enfield Center, NH 03749 · last May 2, first Oct 9
- Danbury, NH 03230 · last May 21, first Sep 26
- Springfield, NH 03284 · last May 2, first Oct 9
- Canaan, NH 03741 · last May 21, first Sep 26
- Wilmot, NH 03287 · last May 14, first Oct 1
- Enfield, NH 03748 · last May 9, first Oct 6
- Grantham, NH 03753 · last May 14, first Oct 1
- Elkins, NH 03233 · last May 14, first Oct 1
Frequently asked questions
- When is the last frost in Grafton, NH?
- For ZIP code 03240, the average last spring frost (32°F) is May 21, based on NOAA 1991-2020 climate normals for the Grafton, NH weather station. There is a 1-in-10 chance of a frost after June 5.
- When is the first frost in Grafton, NH?
- The average first fall frost (32°F) is September 26. There is a 1-in-10 chance of frost by September 12, so tender plants are at risk from that point on.
- How long is the growing season in 03240?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 127 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.