Frost dates for 83647Mountain Home, ID
The average last spring frost in Mountain Home is May 2 and the average first fall frost is October 8, giving a typical growing season of about 157 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 2
- Average first fall frost
- Oct 8
- Growing season
- 157 days
Safer after May 23 (1-in-10 risk)
Possible by Sep 25 (1-in-10 risk)
Last frost typically in 180 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 17 · Jun 10 | Sep 11 · Sep 28 · Oct 11 | 131 days | 100% |
| Frost / freeze (32°F) | Apr 18 · May 2 · May 23 | Sep 25 · Oct 8 · Oct 24 | 157 days | 100% |
| Hard freeze (28°F) | Apr 1 · Apr 18 · May 8 | Oct 4 · Oct 20 · Nov 5 | 185 days | 100% |
Planting calendar for Mountain Home
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 18 |
| 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 28 |
| Summer squash | Sow outdoors | May 18 – Jul 2 |
| Winter squash & pumpkins | Sow outdoors | Jun 1 – Jul 2 |
| Snap beans | Sow outdoors | May 18 – Jul 21 |
| Sweet corn | Sow outdoors | May 18 – Jun 18 |
| 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 8 – Jun 18 |
| Broccoli | Transplant outdoors (fall) | Jul 8 – Jul 19 |
| Cabbage | Start seeds indoors (spring) | Mar 4 – Apr 1 |
| Cabbage | Transplant outdoors (spring) | Apr 1 – May 2 |
| Cabbage | Start seeds indoors (fall) | May 29 – Jun 28 |
| Cabbage | Transplant outdoors (fall) | Jun 28 – Jul 29 |
| Leaf lettuce | Sow outdoors (spring) | Apr 1 – Jun 17 |
| Leaf lettuce | Sow outdoors (fall) | Jun 28 – Aug 14 |
| Spinach | Sow outdoors (spring) | Mar 25 – May 8 |
| Spinach | Sow outdoors (fall) | Jul 15 – Aug 19 |
| Radishes | Sow outdoors (spring) | Apr 1 – May 22 |
| Radishes | Sow outdoors (fall) | Jun 28 – Aug 29 |
| Kale | Sow outdoors (spring) | Apr 18 – May 8 |
| Kale | Sow outdoors (fall) | Jun 21 – Jul 29 |
| Carrots | Sow outdoors (spring) | May 2 – Jun 17 |
| Carrots | Sow outdoors (fall) | May 29 – Jul 14 |
| Garlic | Plant outdoors (fall) | Sep 28 – Oct 29 |
Where these dates come from
ZIP code 83647 is matched to the NOAA station Mtn Home, ID, 1.9 km away, at 3,140 ft elevation (13 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Mtn Home, ID (used) | 3,140 ft | May 2 | Oct 8 |
| Bruneau, ID | 2,530 ft | Apr 17 | Oct 17 |
| Glenns Ferry, ID | 2,466 ft | May 1 | Oct 3 |
| Grand View 4 Nw, ID | 2,400 ft | Apr 28 | Oct 6 |
Frost dates near Mountain Home
- Hammett, ID 83627 · last May 1, first Oct 3
- Grand View, ID 83624 · last Apr 28, first Oct 6
- Glenns Ferry, ID 83623 · last May 1, first Oct 3
- King Hill, ID 83633 · last May 1, first Oct 3
- Boise, ID 83716 · last May 17, first Oct 12
- Hill City, ID 83337 · last Jun 16, first Sep 6
- Bruneau, ID 83604 · last May 17, first Sep 29
- Bliss, ID 83314 · last May 3, first Oct 1
Frequently asked questions
- When is the last frost in Mountain Home, ID?
- For ZIP code 83647, the average last spring frost (32°F) is May 2, based on NOAA 1991-2020 climate normals for the Mtn Home, ID weather station. There is a 1-in-10 chance of a frost after May 23.
- When is the first frost in Mountain Home, ID?
- The average first fall frost (32°F) is October 8. 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 83647?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 157 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.