Frost dates for 59089Wyola, MT
The average last spring frost in Wyola is May 21 and the average first fall frost is September 17, giving a typical growing season of about 117 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 21
- Average first fall frost
- Sep 17
- Growing season
- 117 days
Safer after Jun 2 (1-in-10 risk)
Possible by Sep 5 (1-in-10 risk)
Last frost typically in 206 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 21 · Jun 1 · Jun 26 | Aug 24 · Sep 6 · Sep 19 | 95 days | 100% |
| Frost / freeze (32°F) | May 9 · May 21 · Jun 2 | Sep 5 · Sep 17 · Oct 1 | 117 days | 100% |
| Hard freeze (28°F) | Apr 27 · May 10 · May 24 | Sep 15 · Sep 28 · Oct 9 | 140 days | 100% |
Planting calendar for Wyola
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 20 – Jun 26 |
| Tomatoes | Transplant outdoors | Jun 6 – May 28 |
| Peppers | Start seeds indoors | Apr 20 – May 21 |
| Peppers | Transplant outdoors | Jun 20 – Jul 21 |
| Eggplant | Start seeds indoors | May 7 – Jun 5 |
| Eggplant | Transplant outdoors | Jun 20 – Jul 21 |
| Cucumbers | Sow outdoors | Jun 20 – Jun 7 |
| Summer squash | Sow outdoors | Jun 6 – Jul 21 |
| Winter squash & pumpkins | Sow outdoors | Jun 20 – Jul 21 |
| Snap beans | Sow outdoors | Jun 6 – Jun 30 |
| Sweet corn | Sow outdoors | Jun 6 – May 28 |
| Watermelon & cantaloupe | Sow outdoors | Jun 20 – Jul 21 |
| Okra | Sow outdoors | Jun 13 – Jul 6 |
| Peas | Sow outdoors (spring) | Apr 20 – Jun 5 |
| Potatoes | Plant outdoors (spring) | Apr 20 – Jun 20 |
| Onions | Start seeds indoors (spring) | Mar 9 – Apr 5 |
| Onions | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (spring) | Apr 2 – May 6 |
| Broccoli | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (fall) | May 18 – May 28 |
| Broccoli | Transplant outdoors (fall) | Jun 17 – Jun 28 |
| Cabbage | Start seeds indoors (spring) | Mar 23 – Apr 20 |
| Cabbage | Transplant outdoors (spring) | Apr 20 – May 21 |
| Cabbage | Start seeds indoors (fall) | May 8 – Jun 7 |
| Cabbage | Transplant outdoors (fall) | Jun 7 – Jul 8 |
| Leaf lettuce | Sow outdoors (spring) | Apr 20 – Jul 6 |
| Leaf lettuce | Sow outdoors (fall) | Jun 7 – Jul 24 |
| Spinach | Sow outdoors (spring) | Apr 13 – May 27 |
| Spinach | Sow outdoors (fall) | Jun 24 – Jul 29 |
| Radishes | Sow outdoors (spring) | Apr 20 – Jun 10 |
| Radishes | Sow outdoors (fall) | Jun 7 – Aug 8 |
| Kale | Sow outdoors (spring) | May 7 – May 27 |
| Kale | Sow outdoors (fall) | May 31 – Jul 8 |
| Carrots | Sow outdoors (spring) | May 21 – Jul 6 |
| Carrots | Sow outdoors (fall) | May 8 – Jun 23 |
| Garlic | Plant outdoors (fall) | Sep 7 – Oct 8 |
Where these dates come from
ZIP code 59089 is matched to the NOAA station Wyola 1 Sw, MT, 2.4 km away, at 3,730 ft elevation (33 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Wyola 1 Sw, MT (used) | 3,730 ft | May 21 | Sep 17 |
| Dayton, WY | 3,920 ft | May 24 | Sep 18 |
| Burgess Junction, WY | 8,060 ft | — | — |
| Yellowtail Dam, MT | 3,305 ft | May 7 | Oct 5 |
Frost dates near Wyola
- Parkman, WY 82838 · last May 24, first Sep 18
- Lodge Grass, MT 59050 · last May 23, first Sep 15
- Dayton, WY 82836 · last May 24, first Sep 18
- Ranchester, WY 82839 · last May 24, first Sep 18
- Wolf, WY 82844 · last May 21, first Sep 23
- Decker, MT 59025 · last May 21, first Sep 23
- Fort Smith, MT 59035 · last May 7, first Oct 5
- Garryowen, MT 59031 · last May 7, first Oct 5
Frequently asked questions
- When is the last frost in Wyola, MT?
- For ZIP code 59089, the average last spring frost (32°F) is May 21, based on NOAA 1991-2020 climate normals for the Wyola 1 Sw, MT weather station. There is a 1-in-10 chance of a frost after June 2.
- When is the first frost in Wyola, MT?
- The average first fall frost (32°F) is September 17. There is a 1-in-10 chance of frost by September 5, so tender plants are at risk from that point on.
- How long is the growing season in 59089?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 117 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.