Frost dates for 59633Canyon Creek, MT
The average last spring frost in Canyon Creek is June 4 and the average first fall frost is September 14, giving a typical growing season of about 100 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 4
- Average first fall frost
- Sep 14
- Growing season
- 100 days
Safer after Jun 18 (1-in-10 risk)
Possible by Aug 30 (1-in-10 risk)
Last frost typically in 220 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) | — | — | 71 days | 100% |
| Frost / freeze (32°F) | May 18 · Jun 4 · Jun 18 | Aug 30 · Sep 14 · Sep 27 | 100 days | 100% |
| Hard freeze (28°F) | May 1 · May 14 · May 30 | Sep 12 · Sep 26 · Oct 11 | 134 days | 100% |
Planting calendar for Canyon 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 | May 4 – Jul 10 |
| Tomatoes | Transplant outdoors | Jun 20 – May 25 |
| Peppers | Start seeds indoors | May 4 – Jun 4 |
| Peppers | Transplant outdoors | Jul 4 – Aug 4 |
| Eggplant | Start seeds indoors | May 21 – Jun 19 |
| Eggplant | Transplant outdoors | Jul 4 – Aug 4 |
| Cucumbers | Sow outdoors | Jul 4 – Jun 4 |
| Summer squash | Sow outdoors | Jun 20 – Aug 4 |
| Winter squash & pumpkins | Sow outdoors | Jul 4 – Aug 4 |
| Snap beans | Sow outdoors | Jun 20 – Jun 27 |
| Sweet corn | Sow outdoors | Jun 20 – May 25 |
| Watermelon & cantaloupe | Sow outdoors | Jul 4 – Aug 4 |
| Okra | Sow outdoors | Jun 27 – Jul 20 |
| Peas | Sow outdoors (spring) | May 4 – Jun 19 |
| Potatoes | Plant outdoors (spring) | May 4 – Jul 4 |
| Onions | Start seeds indoors (spring) | Mar 23 – Apr 19 |
| Onions | Transplant outdoors (spring) | May 21 – Jun 19 |
| Broccoli | Start seeds indoors (spring) | Apr 16 – May 20 |
| Broccoli | Transplant outdoors (spring) | May 21 – Jun 19 |
| Broccoli | Start seeds indoors (fall) | May 15 – May 25 |
| Broccoli | Transplant outdoors (fall) | Jun 14 – Jun 25 |
| Cabbage | Start seeds indoors (spring) | Apr 6 – May 4 |
| Cabbage | Transplant outdoors (spring) | May 4 – Jun 4 |
| Cabbage | Start seeds indoors (fall) | May 5 – Jun 4 |
| Cabbage | Transplant outdoors (fall) | Jun 4 – Jul 5 |
| Leaf lettuce | Sow outdoors (spring) | May 4 – Jul 20 |
| Leaf lettuce | Sow outdoors (fall) | Jun 4 – Jul 21 |
| Spinach | Sow outdoors (spring) | Apr 27 – Jun 10 |
| Spinach | Sow outdoors (fall) | Jun 21 – Jul 26 |
| Radishes | Sow outdoors (spring) | May 4 – Jun 24 |
| Radishes | Sow outdoors (fall) | Jun 4 – Aug 5 |
| Kale | Sow outdoors (spring) | May 21 – Jun 10 |
| Kale | Sow outdoors (fall) | May 28 – Jul 5 |
| Carrots | Sow outdoors (spring) | Jun 4 – Jul 20 |
| Carrots | Sow outdoors (fall) | May 5 – Jun 20 |
| Garlic | Plant outdoors (fall) | Sep 4 – Oct 5 |
Where these dates come from
ZIP code 59633 is matched to the NOAA station Austin 1 W, MT, 13.1 km away, at 4,851 ft elevation (451 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Austin 1 W, MT (used) | 4,851 ft | Jun 4 | Sep 14 |
| Elliston, MT | 5,080 ft | Jun 9 | Sep 8 |
| Helena Rgnl Ap, MT | 3,828 ft | May 9 | Sep 30 |
| Holter Dam, MT | 3,487 ft | May 19 | Sep 24 |
Frost dates near Canyon Creek
- Marysville, MT 59640 · last Jun 4, first Sep 14
- Fort Harrison, MT 59636 · last May 9, first Sep 30
- Helena, MT 59602 · last May 9, first Sep 30
- Elliston, MT 59728 · last Jun 9, first Sep 8
- Avon, MT 59713 · last Jun 4, first Sep 14
- East Helena, MT 59635 · last May 9, first Sep 30
- Lincoln, MT 59639 · last —, first —
- Wolf Creek, MT 59648 · last May 21, first Sep 15
Frequently asked questions
- When is the last frost in Canyon Creek, MT?
- For ZIP code 59633, the average last spring frost (32°F) is June 4, based on NOAA 1991-2020 climate normals for the Austin 1 W, MT weather station. There is a 1-in-10 chance of a frost after June 18.
- When is the first frost in Canyon Creek, MT?
- The average first fall frost (32°F) is September 14. There is a 1-in-10 chance of frost by August 30, so tender plants are at risk from that point on.
- How long is the growing season in 59633?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 100 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.