Frost dates for 59874Trout Creek, MT
The average last spring frost in Trout Creek is May 20 and the average first fall frost is September 21, giving a typical growing season of about 122 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 20
- Average first fall frost
- Sep 21
- Growing season
- 122 days
Safer after Jun 9 (1-in-10 risk)
Possible by Sep 2 (1-in-10 risk)
Last frost typically in 205 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) | — | — | 83 days | 100% |
| Frost / freeze (32°F) | May 5 · May 20 · Jun 9 | Sep 2 · Sep 21 · Oct 9 | 122 days | 100% |
| Hard freeze (28°F) | Apr 15 · May 1 · May 17 | Sep 21 · Oct 8 · Nov 1 | 159 days | 100% |
Planting calendar for Trout Creek
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 19 – Jun 25 |
| Tomatoes | Transplant outdoors | Jun 5 – Jun 1 |
| Peppers | Start seeds indoors | Apr 19 – May 20 |
| Peppers | Transplant outdoors | Jun 19 – Jul 20 |
| Eggplant | Start seeds indoors | May 6 – Jun 4 |
| Eggplant | Transplant outdoors | Jun 19 – Jul 20 |
| Cucumbers | Sow outdoors | Jun 19 – Jun 11 |
| Summer squash | Sow outdoors | Jun 5 – Jul 20 |
| Winter squash & pumpkins | Sow outdoors | Jun 19 – Jul 20 |
| Snap beans | Sow outdoors | Jun 5 – Jul 4 |
| Sweet corn | Sow outdoors | Jun 5 – Jun 1 |
| Watermelon & cantaloupe | Sow outdoors | Jun 19 – Jul 20 |
| Okra | Sow outdoors | Jun 12 – Jul 5 |
| Peas | Sow outdoors (spring) | Apr 19 – Jun 4 |
| Potatoes | Plant outdoors (spring) | Apr 19 – Jun 19 |
| Onions | Start seeds indoors (spring) | Mar 8 – Apr 4 |
| Onions | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (spring) | Apr 1 – May 5 |
| Broccoli | Transplant outdoors (spring) | May 6 – Jun 4 |
| Broccoli | Start seeds indoors (fall) | May 22 – Jun 1 |
| Broccoli | Transplant outdoors (fall) | Jun 21 – Jul 2 |
| Cabbage | Start seeds indoors (spring) | Mar 22 – Apr 19 |
| Cabbage | Transplant outdoors (spring) | Apr 19 – May 20 |
| Cabbage | Start seeds indoors (fall) | May 12 – Jun 11 |
| Cabbage | Transplant outdoors (fall) | Jun 11 – Jul 12 |
| Leaf lettuce | Sow outdoors (spring) | Apr 19 – Jul 5 |
| Leaf lettuce | Sow outdoors (fall) | Jun 11 – Jul 28 |
| Spinach | Sow outdoors (spring) | Apr 12 – May 26 |
| Spinach | Sow outdoors (fall) | Jun 28 – Aug 2 |
| Radishes | Sow outdoors (spring) | Apr 19 – Jun 9 |
| Radishes | Sow outdoors (fall) | Jun 11 – Aug 12 |
| Kale | Sow outdoors (spring) | May 6 – May 26 |
| Kale | Sow outdoors (fall) | Jun 4 – Jul 12 |
| Carrots | Sow outdoors (spring) | May 20 – Jul 5 |
| Carrots | Sow outdoors (fall) | May 12 – Jun 27 |
| Garlic | Plant outdoors (fall) | Sep 11 – Oct 12 |
Where these dates come from
ZIP code 59874 is matched to the NOAA station Trout Creek Rs, MT, 8 km away, at 2,356 ft elevation (69 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Trout Creek Rs, MT (used) | 2,356 ft | May 20 | Sep 21 |
| Thompson Falls Ph, MT | 2,380 ft | May 7 | Oct 4 |
| Libby 32 Sse, MT | 3,440 ft | — | — |
| Prichard 3 Ese, ID | 2,547 ft | May 31 | Sep 5 |
Frost dates near Trout Creek
- Thompson Falls, MT 59873 · last May 7, first Oct 4
- Murray, ID 83874 · last May 5, first Oct 2
- Noxon, MT 59853 · last —, first —
- Heron, MT 59844 · last May 20, first Sep 20
- Mullan, ID 83846 · last May 12, first Sep 30
- Saltese, MT 59867 · last —, first —
- Silverton, ID 83867 · last May 5, first Oct 2
- Wallace, ID 83873 · last May 5, first Oct 2
Frequently asked questions
- When is the last frost in Trout Creek, MT?
- For ZIP code 59874, the average last spring frost (32°F) is May 20, based on NOAA 1991-2020 climate normals for the Trout Creek Rs, MT weather station. There is a 1-in-10 chance of a frost after June 9.
- When is the first frost in Trout Creek, MT?
- The average first fall frost (32°F) is September 21. There is a 1-in-10 chance of frost by September 2, so tender plants are at risk from that point on.
- How long is the growing season in 59874?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 122 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.