Frost dates for 83687Nampa, ID
The average last spring frost in Nampa is April 29 and the average first fall frost is October 13, giving a typical growing season of about 164 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 29
- Average first fall frost
- Oct 13
- Growing season
- 164 days
Safer after May 18 (1-in-10 risk)
Possible by Sep 29 (1-in-10 risk)
Last frost typically in 177 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 1 · May 16 · Jun 6 | Sep 15 · Sep 30 · Oct 14 | 134 days | 100% |
| Frost / freeze (32°F) | Apr 15 · Apr 29 · May 18 | Sep 29 · Oct 13 · Oct 28 | 164 days | 100% |
| Hard freeze (28°F) | Mar 25 · Apr 11 · May 1 | Oct 9 · Oct 25 · Nov 10 | 195 days | 100% |
Planting calendar for Nampa
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 29 – Jun 4 |
| Tomatoes | Transplant outdoors | May 15 – Jun 23 |
| Peppers | Start seeds indoors | Mar 29 – Apr 29 |
| Peppers | Transplant outdoors | May 29 – Jun 29 |
| Eggplant | Start seeds indoors | Apr 15 – May 14 |
| Eggplant | Transplant outdoors | May 29 – Jun 29 |
| Cucumbers | Sow outdoors | May 29 – Jul 3 |
| Summer squash | Sow outdoors | May 15 – Jun 29 |
| Winter squash & pumpkins | Sow outdoors | May 29 – Jun 29 |
| Snap beans | Sow outdoors | May 15 – Jul 26 |
| Sweet corn | Sow outdoors | May 15 – Jun 23 |
| Watermelon & cantaloupe | Sow outdoors | May 29 – Jun 29 |
| Okra | Sow outdoors | May 22 – Jun 14 |
| Peas | Sow outdoors (spring) | Mar 29 – May 14 |
| Potatoes | Plant outdoors (spring) | Mar 29 – May 29 |
| Onions | Start seeds indoors (spring) | Feb 15 – Mar 14 |
| Onions | Transplant outdoors (spring) | Apr 15 – May 14 |
| Broccoli | Start seeds indoors (spring) | Mar 11 – Apr 14 |
| Broccoli | Transplant outdoors (spring) | Apr 15 – May 14 |
| Broccoli | Start seeds indoors (fall) | Jun 13 – Jun 23 |
| Broccoli | Transplant outdoors (fall) | Jul 13 – Jul 24 |
| Cabbage | Start seeds indoors (spring) | Mar 1 – Mar 29 |
| Cabbage | Transplant outdoors (spring) | Mar 29 – Apr 29 |
| Cabbage | Start seeds indoors (fall) | Jun 3 – Jul 3 |
| Cabbage | Transplant outdoors (fall) | Jul 3 – Aug 3 |
| Leaf lettuce | Sow outdoors (spring) | Mar 29 – Jun 14 |
| Leaf lettuce | Sow outdoors (fall) | Jul 3 – Aug 19 |
| Spinach | Sow outdoors (spring) | Mar 22 – May 5 |
| Spinach | Sow outdoors (fall) | Jul 20 – Aug 24 |
| Radishes | Sow outdoors (spring) | Mar 29 – May 19 |
| Radishes | Sow outdoors (fall) | Jul 3 – Sep 3 |
| Kale | Sow outdoors (spring) | Apr 15 – May 5 |
| Kale | Sow outdoors (fall) | Jun 26 – Aug 3 |
| Carrots | Sow outdoors (spring) | Apr 29 – Jun 14 |
| Carrots | Sow outdoors (fall) | Jun 3 – Jul 19 |
| Garlic | Plant outdoors (fall) | Oct 3 – Nov 3 |
Where these dates come from
ZIP code 83687 is matched to the NOAA station Nampa Sugar Factory, ID, 3.4 km away, at 2,470 ft elevation (66 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Nampa Sugar Factory, ID (used) | 2,470 ft | Apr 29 | Oct 13 |
| Deer Flat Dam, ID | 2,510 ft | Apr 23 | Oct 18 |
| Boise Air Terminal, ID | 2,814 ft | Apr 24 | Oct 21 |
| Emmett 2 E, ID | 2,390 ft | Apr 30 | Oct 17 |
Frost dates near Nampa
- Nampa, ID 83651 · last Apr 29, first Oct 13
- Meridian, ID 83646 · last Apr 29, first Oct 13
- Star, ID 83669 · last Apr 29, first Oct 13
- Middleton, ID 83644 · last Apr 29, first Oct 13
- Caldwell, ID 83605 · last Apr 29, first Oct 13
- Boise, ID 83713 · last Apr 24, first Oct 21
- Kuna, ID 83634 · last Apr 24, first Oct 21
- Eagle, ID 83616 · last Apr 29, first Oct 13
Frequently asked questions
- When is the last frost in Nampa, ID?
- For ZIP code 83687, the average last spring frost (32°F) is April 29, based on NOAA 1991-2020 climate normals for the Nampa Sugar Factory, ID weather station. There is a 1-in-10 chance of a frost after May 18.
- When is the first frost in Nampa, ID?
- The average first fall frost (32°F) is October 13. There is a 1-in-10 chance of frost by September 29, so tender plants are at risk from that point on.
- How long is the growing season in 83687?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 164 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.