Frost dates for 59076Sanders, MT
The average last spring frost in Sanders is May 10 and the average first fall frost is September 29, giving a typical growing season of about 141 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 10
- Average first fall frost
- Sep 29
- Growing season
- 141 days
Safer after May 22 (1-in-10 risk)
Possible by Sep 15 (1-in-10 risk)
Last frost typically in 195 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 9 · May 21 · Jun 1 | Sep 7 · Sep 20 · Oct 2 | 121 days | 100% |
| Frost / freeze (32°F) | Apr 28 · May 10 · May 22 | Sep 15 · Sep 29 · Oct 11 | 141 days | 100% |
| Hard freeze (28°F) | Apr 14 · Apr 30 · May 13 | Sep 24 · Oct 7 · Oct 21 | 161 days | 100% |
Planting calendar for Sanders
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 9 – Jun 15 |
| Tomatoes | Transplant outdoors | May 26 – Jun 9 |
| Peppers | Start seeds indoors | Apr 9 – May 10 |
| Peppers | Transplant outdoors | Jun 9 – Jul 10 |
| Eggplant | Start seeds indoors | Apr 26 – May 25 |
| Eggplant | Transplant outdoors | Jun 9 – Jul 10 |
| Cucumbers | Sow outdoors | Jun 9 – Jun 19 |
| Summer squash | Sow outdoors | May 26 – Jul 10 |
| Winter squash & pumpkins | Sow outdoors | Jun 9 – Jul 10 |
| Snap beans | Sow outdoors | May 26 – Jul 12 |
| Sweet corn | Sow outdoors | May 26 – Jun 9 |
| Watermelon & cantaloupe | Sow outdoors | Jun 9 – Jul 10 |
| Okra | Sow outdoors | Jun 2 – Jun 25 |
| Peas | Sow outdoors (spring) | Apr 9 – May 25 |
| Potatoes | Plant outdoors (spring) | Apr 9 – Jun 9 |
| Onions | Start seeds indoors (spring) | Feb 26 – Mar 25 |
| Onions | Transplant outdoors (spring) | Apr 26 – May 25 |
| Broccoli | Start seeds indoors (spring) | Mar 22 – Apr 25 |
| Broccoli | Transplant outdoors (spring) | Apr 26 – May 25 |
| Broccoli | Start seeds indoors (fall) | May 30 – Jun 9 |
| Broccoli | Transplant outdoors (fall) | Jun 29 – Jul 10 |
| Cabbage | Start seeds indoors (spring) | Mar 12 – Apr 9 |
| Cabbage | Transplant outdoors (spring) | Apr 9 – May 10 |
| Cabbage | Start seeds indoors (fall) | May 20 – Jun 19 |
| Cabbage | Transplant outdoors (fall) | Jun 19 – Jul 20 |
| Leaf lettuce | Sow outdoors (spring) | Apr 9 – Jun 25 |
| Leaf lettuce | Sow outdoors (fall) | Jun 19 – Aug 5 |
| Spinach | Sow outdoors (spring) | Apr 2 – May 16 |
| Spinach | Sow outdoors (fall) | Jul 6 – Aug 10 |
| Radishes | Sow outdoors (spring) | Apr 9 – May 30 |
| Radishes | Sow outdoors (fall) | Jun 19 – Aug 20 |
| Kale | Sow outdoors (spring) | Apr 26 – May 16 |
| Kale | Sow outdoors (fall) | Jun 12 – Jul 20 |
| Carrots | Sow outdoors (spring) | May 10 – Jun 25 |
| Carrots | Sow outdoors (fall) | May 20 – Jul 5 |
| Garlic | Plant outdoors (fall) | Sep 19 – Oct 20 |
Where these dates come from
ZIP code 59076 is matched to the NOAA station Hysham, MT, 10.3 km away, at 2,669 ft elevation (64 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Hysham, MT (used) | 2,669 ft | May 10 | Sep 29 |
| Ingomar 9 E, MT | 2,800 ft | May 21 | Sep 19 |
| Forsyth, MT | 2,515 ft | May 9 | Sep 29 |
| Hysham 25 Sse, MT | 3,100 ft | May 26 | Sep 16 |
Frost dates near Sanders
- Hysham, MT 59038 · last May 10, first Sep 29
- Forsyth, MT 59327 · last May 9, first Sep 29
- Bighorn, MT 59010 · last May 26, first Sep 16
- Ingomar, MT 59039 · last May 21, first Sep 19
- Custer, MT 59024 · last May 10, first Sep 29
- Sumatra, MT 59083 · last May 10, first Sep 29
- Colstrip, MT 59323 · last May 15, first Sep 30
- Rosebud, MT 59347 · last May 9, first Sep 29
Frequently asked questions
- When is the last frost in Sanders, MT?
- For ZIP code 59076, the average last spring frost (32°F) is May 10, based on NOAA 1991-2020 climate normals for the Hysham, MT weather station. There is a 1-in-10 chance of a frost after May 22.
- When is the first frost in Sanders, MT?
- The average first fall frost (32°F) is September 29. There is a 1-in-10 chance of frost by September 15, so tender plants are at risk from that point on.
- How long is the growing season in 59076?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 141 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.