Frost dates for 83716Boise, ID
The average last spring frost in Boise is May 17 and the average first fall frost is October 12, giving a typical growing season of about 147 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 17
- Average first fall frost
- Oct 12
- Growing season
- 147 days
Safer after Jun 10 (1-in-10 risk)
Possible by Sep 27 (1-in-10 risk)
Last frost typically in 202 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 18 · Jun 6 · Jun 23 | Sep 13 · Sep 29 · Oct 16 | 114 days | 100% |
| Frost / freeze (32°F) | Apr 27 · May 17 · Jun 10 | Sep 27 · Oct 12 · Oct 30 | 147 days | 100% |
| Hard freeze (28°F) | Apr 7 · Apr 27 · May 19 | Oct 8 · Oct 24 · Nov 11 | 179 days | 100% |
Planting calendar for Boise
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 16 – Jun 22 |
| Tomatoes | Transplant outdoors | Jun 2 – Jun 22 |
| Peppers | Start seeds indoors | Apr 16 – May 17 |
| Peppers | Transplant outdoors | Jun 16 – Jul 17 |
| Eggplant | Start seeds indoors | May 3 – Jun 1 |
| Eggplant | Transplant outdoors | Jun 16 – Jul 17 |
| Cucumbers | Sow outdoors | Jun 16 – Jul 2 |
| Summer squash | Sow outdoors | Jun 2 – Jul 17 |
| Winter squash & pumpkins | Sow outdoors | Jun 16 – Jul 17 |
| Snap beans | Sow outdoors | Jun 2 – Jul 25 |
| Sweet corn | Sow outdoors | Jun 2 – Jun 22 |
| Watermelon & cantaloupe | Sow outdoors | Jun 16 – Jul 17 |
| Okra | Sow outdoors | Jun 9 – Jul 2 |
| Peas | Sow outdoors (spring) | Apr 16 – Jun 1 |
| Potatoes | Plant outdoors (spring) | Apr 16 – Jun 16 |
| Onions | Start seeds indoors (spring) | Mar 5 – Apr 1 |
| Onions | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (spring) | Mar 29 – May 2 |
| Broccoli | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (fall) | Jun 12 – Jun 22 |
| Broccoli | Transplant outdoors (fall) | Jul 12 – Jul 23 |
| Cabbage | Start seeds indoors (spring) | Mar 19 – Apr 16 |
| Cabbage | Transplant outdoors (spring) | Apr 16 – May 17 |
| Cabbage | Start seeds indoors (fall) | Jun 2 – Jul 2 |
| Cabbage | Transplant outdoors (fall) | Jul 2 – Aug 2 |
| Leaf lettuce | Sow outdoors (spring) | Apr 16 – Jul 2 |
| Leaf lettuce | Sow outdoors (fall) | Jul 2 – Aug 18 |
| Spinach | Sow outdoors (spring) | Apr 9 – May 23 |
| Spinach | Sow outdoors (fall) | Jul 19 – Aug 23 |
| Radishes | Sow outdoors (spring) | Apr 16 – Jun 6 |
| Radishes | Sow outdoors (fall) | Jul 2 – Sep 2 |
| Kale | Sow outdoors (spring) | May 3 – May 23 |
| Kale | Sow outdoors (fall) | Jun 25 – Aug 2 |
| Carrots | Sow outdoors (spring) | May 17 – Jul 2 |
| Carrots | Sow outdoors (fall) | Jun 2 – Jul 18 |
| Garlic | Plant outdoors (fall) | Oct 2 – Nov 2 |
Where these dates come from
ZIP code 83716 is matched to the NOAA station Boise 7 N, ID, 29.3 km away, at 3,885 ft elevation (65 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Boise 7 N, ID (used) | 3,885 ft | May 17 | Oct 12 |
| Boise Lucky Peak Dam, ID | 2,840 ft | Apr 30 | Oct 22 |
| Arrowrock Dam, ID | 3,235 ft | Apr 28 | Oct 14 |
| Boise Air Terminal, ID | 2,814 ft | Apr 24 | Oct 21 |
Frost dates near Boise
- Boise, ID 83712 · last Apr 24, first Oct 21
- Garden City, ID 83714 · last Apr 24, first Oct 21
- Kuna, ID 83634 · last Apr 24, first Oct 21
- Meridian, ID 83680 · last Apr 29, first Oct 13
- Eagle, ID 83616 · last Apr 29, first Oct 13
- Idaho City, ID 83631 · last Jun 17, first Sep 5
- Mountain Home Afb, ID 83648 · last Apr 30, first Oct 17
- Nampa, ID 83687 · last Apr 29, first Oct 13
Frequently asked questions
- When is the last frost in Boise, ID?
- For ZIP code 83716, the average last spring frost (32°F) is May 17, based on NOAA 1991-2020 climate normals for the Boise 7 N, ID weather station. There is a 1-in-10 chance of a frost after June 10.
- When is the first frost in Boise, ID?
- The average first fall frost (32°F) is October 12. There is a 1-in-10 chance of frost by September 27, so tender plants are at risk from that point on.
- How long is the growing season in 83716?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 147 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.