Frost dates for 83450Terreton, ID
The average last spring frost in Terreton is June 3 and the average first fall frost is September 11, giving a typical growing season of about 98 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 3
- Average first fall frost
- Sep 11
- Growing season
- 98 days
Safer after Jun 21 (1-in-10 risk)
Possible by Aug 30 (1-in-10 risk)
Last frost typically in 219 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) | — | — | 70 days | 100% |
| Frost / freeze (32°F) | May 15 · Jun 3 · Jun 21 | Aug 30 · Sep 11 · Sep 24 | 98 days | 100% |
| Hard freeze (28°F) | May 2 · May 14 · Jun 2 | Sep 5 · Sep 21 · Oct 6 | 127 days | 100% |
Planting calendar for Terreton
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 | May 3 – Jul 9 |
| Tomatoes | Transplant outdoors | Jun 19 – May 22 |
| Peppers | Start seeds indoors | May 3 – Jun 3 |
| Peppers | Transplant outdoors | Jul 3 – Aug 3 |
| Eggplant | Start seeds indoors | May 20 – Jun 18 |
| Eggplant | Transplant outdoors | Jul 3 – Aug 3 |
| Cucumbers | Sow outdoors | Jul 3 – Jun 1 |
| Summer squash | Sow outdoors | Jun 19 – Aug 3 |
| Winter squash & pumpkins | Sow outdoors | Jul 3 – Aug 3 |
| Snap beans | Sow outdoors | Jun 19 – Jun 24 |
| Sweet corn | Sow outdoors | Jun 19 – May 22 |
| Watermelon & cantaloupe | Sow outdoors | Jul 3 – Aug 3 |
| Okra | Sow outdoors | Jun 26 – Jul 19 |
| Peas | Sow outdoors (spring) | May 3 – Jun 18 |
| Potatoes | Plant outdoors (spring) | May 3 – Jul 3 |
| Onions | Start seeds indoors (spring) | Mar 22 – Apr 18 |
| Onions | Transplant outdoors (spring) | May 20 – Jun 18 |
| Broccoli | Start seeds indoors (spring) | Apr 15 – May 19 |
| Broccoli | Transplant outdoors (spring) | May 20 – Jun 18 |
| Broccoli | Start seeds indoors (fall) | May 12 – May 22 |
| Broccoli | Transplant outdoors (fall) | Jun 11 – Jun 22 |
| Cabbage | Start seeds indoors (spring) | Apr 5 – May 3 |
| Cabbage | Transplant outdoors (spring) | May 3 – Jun 3 |
| Cabbage | Start seeds indoors (fall) | May 2 – Jun 1 |
| Cabbage | Transplant outdoors (fall) | Jun 1 – Jul 2 |
| Leaf lettuce | Sow outdoors (spring) | May 3 – Jul 19 |
| Leaf lettuce | Sow outdoors (fall) | Jun 1 – Jul 18 |
| Spinach | Sow outdoors (spring) | Apr 26 – Jun 9 |
| Spinach | Sow outdoors (fall) | Jun 18 – Jul 23 |
| Radishes | Sow outdoors (spring) | May 3 – Jun 23 |
| Radishes | Sow outdoors (fall) | Jun 1 – Aug 2 |
| Kale | Sow outdoors (spring) | May 20 – Jun 9 |
| Kale | Sow outdoors (fall) | May 25 – Jul 2 |
| Carrots | Sow outdoors (spring) | Jun 3 – Jul 19 |
| Carrots | Sow outdoors (fall) | May 2 – Jun 17 |
| Garlic | Plant outdoors (fall) | Sep 1 – Oct 2 |
Where these dates come from
ZIP code 83450 is matched to the NOAA station Hamer 4 Nw, ID, 17.3 km away, at 4,790 ft elevation (7 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Hamer 4 Nw, ID (used) | 4,790 ft | Jun 3 | Sep 11 |
| Monteview, ID | 4,815 ft | Jun 12 | Sep 7 |
| Rigby, ID | 4,856 ft | May 9 | Oct 5 |
| Dubois Exp Stn, ID | 5,450 ft | May 18 | Sep 30 |
Frost dates near Terreton
- Monteview, ID 83435 · last Jun 12, first Sep 7
- Hamer, ID 83425 · last Jun 3, first Sep 11
- Roberts, ID 83444 · last May 23, first Sep 20
- Dubois, ID 83423 · last May 18, first Sep 30
- Menan, ID 83434 · last May 15, first Sep 23
- Lewisville, ID 83431 · last May 9, first Oct 1
- Rigby, ID 83442 · last May 9, first Oct 5
- Ucon, ID 83454 · last May 9, first Oct 1
Frequently asked questions
- When is the last frost in Terreton, ID?
- For ZIP code 83450, the average last spring frost (32°F) is June 3, based on NOAA 1991-2020 climate normals for the Hamer 4 Nw, ID weather station. There is a 1-in-10 chance of a frost after June 21.
- When is the first frost in Terreton, ID?
- The average first fall frost (32°F) is September 11. There is a 1-in-10 chance of frost by August 30, so tender plants are at risk from that point on.
- How long is the growing season in 83450?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 98 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.