Frost dates for 59710Alder, MT
The average last spring frost in Alder is June 6 and the average first fall frost is September 14, giving a typical growing season of about 98 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 6
- Average first fall frost
- Sep 14
- Growing season
- 98 days
Safer after Jun 25 (1-in-10 risk)
Possible by Aug 31 (1-in-10 risk)
Last frost typically in 222 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) | — | — | 68 days | 100% |
| Frost / freeze (32°F) | May 20 · Jun 6 · Jun 25 | Aug 31 · Sep 14 · Sep 27 | 98 days | 100% |
| Hard freeze (28°F) | May 3 · May 16 · Jun 1 | Sep 9 · Sep 26 · Oct 10 | 131 days | 100% |
Planting calendar for Alder
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 6 – Jul 12 |
| Tomatoes | Transplant outdoors | Jun 22 – May 25 |
| Peppers | Start seeds indoors | May 6 – Jun 6 |
| Peppers | Transplant outdoors | Jul 6 – Aug 6 |
| Eggplant | Start seeds indoors | May 23 – Jun 21 |
| Eggplant | Transplant outdoors | Jul 6 – Aug 6 |
| Cucumbers | Sow outdoors | Jul 6 – Jun 4 |
| Summer squash | Sow outdoors | Jun 22 – Aug 6 |
| Winter squash & pumpkins | Sow outdoors | Jul 6 – Aug 6 |
| Snap beans | Sow outdoors | Jun 22 – Jun 27 |
| Sweet corn | Sow outdoors | Jun 22 – May 25 |
| Watermelon & cantaloupe | Sow outdoors | Jul 6 – Aug 6 |
| Okra | Sow outdoors | Jun 29 – Jul 22 |
| Peas | Sow outdoors (spring) | May 6 – Jun 21 |
| Potatoes | Plant outdoors (spring) | May 6 – Jul 6 |
| Onions | Start seeds indoors (spring) | Mar 25 – Apr 21 |
| Onions | Transplant outdoors (spring) | May 23 – Jun 21 |
| Broccoli | Start seeds indoors (spring) | Apr 18 – May 22 |
| Broccoli | Transplant outdoors (spring) | May 23 – Jun 21 |
| Broccoli | Start seeds indoors (fall) | May 15 – May 25 |
| Broccoli | Transplant outdoors (fall) | Jun 14 – Jun 25 |
| Cabbage | Start seeds indoors (spring) | Apr 8 – May 6 |
| Cabbage | Transplant outdoors (spring) | May 6 – Jun 6 |
| Cabbage | Start seeds indoors (fall) | May 5 – Jun 4 |
| Cabbage | Transplant outdoors (fall) | Jun 4 – Jul 5 |
| Leaf lettuce | Sow outdoors (spring) | May 6 – Jul 22 |
| Leaf lettuce | Sow outdoors (fall) | Jun 4 – Jul 21 |
| Spinach | Sow outdoors (spring) | Apr 29 – Jun 12 |
| Spinach | Sow outdoors (fall) | Jun 21 – Jul 26 |
| Radishes | Sow outdoors (spring) | May 6 – Jun 26 |
| Radishes | Sow outdoors (fall) | Jun 4 – Aug 5 |
| Kale | Sow outdoors (spring) | May 23 – Jun 12 |
| Kale | Sow outdoors (fall) | May 28 – Jul 5 |
| Carrots | Sow outdoors (spring) | Jun 6 – Jul 22 |
| Carrots | Sow outdoors (fall) | May 5 – Jun 20 |
| Garlic | Plant outdoors (fall) | Sep 4 – Oct 5 |
Where these dates come from
ZIP code 59710 is matched to the NOAA station Alder 17 S, MT, 13.7 km away, at 5,850 ft elevation (1,240 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Alder 17 S, MT (used) | 5,850 ft | Jun 6 | Sep 14 |
| Alder 19S, MT | 5,749 ft | — | — |
| Virginia City, MT | 5,773 ft | Jun 4 | Sep 18 |
| Laurin 2Ne, MT | 5,198 ft | May 24 | Sep 22 |
Frost dates near Alder
- Virginia City, MT 59755 · last Jun 4, first Sep 18
- Sheridan, MT 59749 · last May 24, first Sep 22
- Mc Allister, MT 59740 · last Jun 16, first Sep 4
- Cameron, MT 59720 · last Jun 4, first Sep 18
- Ennis, MT 59729 · last Jun 16, first Sep 4
- Twin Bridges, MT 59754 · last Jun 8, first Sep 2
- Dillon, MT 59725 · last Jun 5, first Sep 13
- Norris, MT 59745 · last Apr 30, first Oct 10
Frequently asked questions
- When is the last frost in Alder, MT?
- For ZIP code 59710, the average last spring frost (32°F) is June 6, based on NOAA 1991-2020 climate normals for the Alder 17 S, MT weather station. There is a 1-in-10 chance of a frost after June 25.
- When is the first frost in Alder, MT?
- The average first fall frost (32°F) is September 14. There is a 1-in-10 chance of frost by August 31, so tender plants are at risk from that point on.
- How long is the growing season in 59710?
- 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.