Frost dates for 83655New Plymouth, ID
The average last spring frost in New Plymouth is April 23 and the average first fall frost is October 13, giving a typical growing season of about 173 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 23
- Average first fall frost
- Oct 13
- Growing season
- 173 days
Safer after May 9 (1-in-10 risk)
Possible by Oct 1 (1-in-10 risk)
Last frost typically in 172 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 22 · May 6 · May 24 | Sep 20 · Oct 2 · Oct 16 | 147 days | 100% |
| Frost / freeze (32°F) | Apr 6 · Apr 23 · May 9 | Oct 1 · Oct 13 · Oct 29 | 173 days | 100% |
| Hard freeze (28°F) | Mar 15 · Apr 6 · Apr 25 | Oct 12 · Oct 26 · Nov 10 | 204 days | 100% |
Planting calendar for New Plymouth
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 23 – May 29 |
| Tomatoes | Transplant outdoors | May 9 – Jun 23 |
| Peppers | Start seeds indoors | Mar 23 – Apr 23 |
| Peppers | Transplant outdoors | May 23 – Jun 23 |
| Eggplant | Start seeds indoors | Apr 9 – May 8 |
| Eggplant | Transplant outdoors | May 23 – Jun 23 |
| Cucumbers | Sow outdoors | May 23 – Jul 3 |
| Summer squash | Sow outdoors | May 9 – Jun 23 |
| Winter squash & pumpkins | Sow outdoors | May 23 – Jun 23 |
| Snap beans | Sow outdoors | May 9 – Jul 26 |
| Sweet corn | Sow outdoors | May 9 – Jun 23 |
| Watermelon & cantaloupe | Sow outdoors | May 23 – Jun 23 |
| Okra | Sow outdoors | May 16 – Jun 8 |
| Peas | Sow outdoors (spring) | Mar 23 – May 8 |
| Potatoes | Plant outdoors (spring) | Mar 23 – May 23 |
| Onions | Start seeds indoors (spring) | Feb 9 – Mar 8 |
| Onions | Transplant outdoors (spring) | Apr 9 – May 8 |
| Broccoli | Start seeds indoors (spring) | Mar 5 – Apr 8 |
| Broccoli | Transplant outdoors (spring) | Apr 9 – May 8 |
| Broccoli | Start seeds indoors (fall) | Jun 13 – Jun 23 |
| Broccoli | Transplant outdoors (fall) | Jul 13 – Jul 24 |
| Cabbage | Start seeds indoors (spring) | Feb 23 – Mar 23 |
| Cabbage | Transplant outdoors (spring) | Mar 23 – Apr 23 |
| Cabbage | Start seeds indoors (fall) | Jun 3 – Jul 3 |
| Cabbage | Transplant outdoors (fall) | Jul 3 – Aug 3 |
| Leaf lettuce | Sow outdoors (spring) | Mar 23 – Jun 8 |
| Leaf lettuce | Sow outdoors (fall) | Jul 3 – Aug 19 |
| Spinach | Sow outdoors (spring) | Mar 16 – Apr 29 |
| Spinach | Sow outdoors (fall) | Jul 20 – Aug 24 |
| Radishes | Sow outdoors (spring) | Mar 23 – May 13 |
| Radishes | Sow outdoors (fall) | Jul 3 – Sep 3 |
| Kale | Sow outdoors (spring) | Apr 9 – Apr 29 |
| Kale | Sow outdoors (fall) | Jun 26 – Aug 3 |
| Carrots | Sow outdoors (spring) | Apr 23 – Jun 8 |
| Carrots | Sow outdoors (fall) | Jun 3 – Jul 19 |
| Garlic | Plant outdoors (fall) | Oct 3 – Nov 3 |
Where these dates come from
ZIP code 83655 is matched to the NOAA station Malheur Branch Exp Stn, OR, 17.7 km away, at 2,260 ft elevation (17 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Malheur Branch Exp Stn, OR (used) | 2,260 ft | Apr 23 | Oct 13 |
| Ontario Ksrv, OR | 2,145 ft | Apr 22 | Oct 9 |
| Payette, ID | 2,150 ft | Apr 19 | Oct 20 |
| Nyssa, OR | 2,175 ft | Apr 18 | Oct 18 |
Frost dates near New Plymouth
- Fruitland, ID 83619 · last Apr 21, first Oct 14
- Letha, ID 83636 · last Apr 30, first Oct 17
- Payette, ID 83661 · last Apr 19, first Oct 20
- Ontario, OR 97914 · last Apr 22, first Oct 9
- Nyssa, OR 97913 · last Apr 18, first Oct 18
- Parma, ID 83660 · last Apr 27, first Oct 9
- Emmett, ID 83617 · last Apr 30, first Oct 17
- Notus, ID 83656 · last Apr 27, first Oct 9
Frequently asked questions
- When is the last frost in New Plymouth, ID?
- For ZIP code 83655, the average last spring frost (32°F) is April 23, based on NOAA 1991-2020 climate normals for the Malheur Branch Exp Stn, OR weather station. There is a 1-in-10 chance of a frost after May 9.
- When is the first frost in New Plymouth, ID?
- The average first fall frost (32°F) is October 13. There is a 1-in-10 chance of frost by October 1, so tender plants are at risk from that point on.
- How long is the growing season in 83655?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 173 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.