Frost dates for 59644Townsend, MT
The average last spring frost in Townsend is May 19 and the average first fall frost is September 19, giving a typical growing season of about 122 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 19
- Average first fall frost
- Sep 19
- Growing season
- 122 days
Safer after Jun 2 (1-in-10 risk)
Possible by Sep 5 (1-in-10 risk)
Last frost typically in 204 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 22 · Jun 5 · Jun 23 | Aug 25 · Sep 7 · Sep 21 | 92 days | 100% |
| Frost / freeze (32°F) | May 8 · May 19 · Jun 2 | Sep 5 · Sep 19 · Oct 2 | 122 days | 100% |
| Hard freeze (28°F) | Apr 26 · May 7 · May 20 | Sep 17 · Oct 1 · Oct 14 | 145 days | 100% |
Planting calendar for Townsend
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 18 – Jun 24 |
| Tomatoes | Transplant outdoors | Jun 4 – May 30 |
| Peppers | Start seeds indoors | Apr 18 – May 19 |
| Peppers | Transplant outdoors | Jun 18 – Jul 19 |
| Eggplant | Start seeds indoors | May 5 – Jun 3 |
| Eggplant | Transplant outdoors | Jun 18 – Jul 19 |
| Cucumbers | Sow outdoors | Jun 18 – Jun 9 |
| Summer squash | Sow outdoors | Jun 4 – Jul 19 |
| Winter squash & pumpkins | Sow outdoors | Jun 18 – Jul 19 |
| Snap beans | Sow outdoors | Jun 4 – Jul 2 |
| Sweet corn | Sow outdoors | Jun 4 – May 30 |
| Watermelon & cantaloupe | Sow outdoors | Jun 18 – Jul 19 |
| Okra | Sow outdoors | Jun 11 – Jul 4 |
| Peas | Sow outdoors (spring) | Apr 18 – Jun 3 |
| Potatoes | Plant outdoors (spring) | Apr 18 – Jun 18 |
| Onions | Start seeds indoors (spring) | Mar 7 – Apr 3 |
| Onions | Transplant outdoors (spring) | May 5 – Jun 3 |
| Broccoli | Start seeds indoors (spring) | Mar 31 – May 4 |
| Broccoli | Transplant outdoors (spring) | May 5 – Jun 3 |
| Broccoli | Start seeds indoors (fall) | May 20 – May 30 |
| Broccoli | Transplant outdoors (fall) | Jun 19 – Jun 30 |
| Cabbage | Start seeds indoors (spring) | Mar 21 – Apr 18 |
| Cabbage | Transplant outdoors (spring) | Apr 18 – May 19 |
| Cabbage | Start seeds indoors (fall) | May 10 – Jun 9 |
| Cabbage | Transplant outdoors (fall) | Jun 9 – Jul 10 |
| Leaf lettuce | Sow outdoors (spring) | Apr 18 – Jul 4 |
| Leaf lettuce | Sow outdoors (fall) | Jun 9 – Jul 26 |
| Spinach | Sow outdoors (spring) | Apr 11 – May 25 |
| Spinach | Sow outdoors (fall) | Jun 26 – Jul 31 |
| Radishes | Sow outdoors (spring) | Apr 18 – Jun 8 |
| Radishes | Sow outdoors (fall) | Jun 9 – Aug 10 |
| Kale | Sow outdoors (spring) | May 5 – May 25 |
| Kale | Sow outdoors (fall) | Jun 2 – Jul 10 |
| Carrots | Sow outdoors (spring) | May 19 – Jul 4 |
| Carrots | Sow outdoors (fall) | May 10 – Jun 25 |
| Garlic | Plant outdoors (fall) | Sep 9 – Oct 10 |
Where these dates come from
ZIP code 59644 is matched to the NOAA station Townsend 3Se, MT, 5 km away, at 3,964 ft elevation (135 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Townsend 3Se, MT (used) | 3,964 ft | May 19 | Sep 19 |
| Tizer Gardens, MT | 4,672 ft | Jun 18 | Sep 5 |
| Trident, MT | 4,036 ft | May 9 | Sep 27 |
| Helena Rgnl Ap, MT | 3,828 ft | May 9 | Sep 30 |
Frost dates near Townsend
- Radersburg, MT 59641 · last May 19, first Sep 19
- Winston, MT 59647 · last May 19, first Sep 19
- Toston, MT 59643 · last May 19, first Sep 19
- Clancy, MT 59634 · last May 9, first Sep 30
- Jefferson City, MT 59638 · last Jun 7, first Sep 8
- East Helena, MT 59635 · last May 9, first Sep 30
- White Sulphur Springs, MT 59645 · last Jun 4, first Sep 11
- Boulder, MT 59632 · last Jun 7, first Sep 8
Frequently asked questions
- When is the last frost in Townsend, MT?
- For ZIP code 59644, the average last spring frost (32°F) is May 19, based on NOAA 1991-2020 climate normals for the Townsend 3Se, MT weather station. There is a 1-in-10 chance of a frost after June 2.
- When is the first frost in Townsend, MT?
- The average first fall frost (32°F) is September 19. 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 59644?
- 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.