Frost dates for 59453Judith Gap, MT
The average last spring frost in Judith Gap is June 1 and the average first fall frost is September 15, giving a typical growing season of about 104 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 1
- Average first fall frost
- Sep 15
- Growing season
- 104 days
Safer after Jun 16 (1-in-10 risk)
Possible by Aug 31 (1-in-10 risk)
Last frost typically in 210 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) | — | — | 76 days | 100% |
| Frost / freeze (32°F) | May 17 · Jun 1 · Jun 16 | Aug 31 · Sep 15 · Sep 28 | 104 days | 100% |
| Hard freeze (28°F) | May 3 · May 15 · May 31 | Sep 11 · Sep 28 · Oct 9 | 134 days | 100% |
Planting calendar for Judith Gap
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 1 – Jul 7 |
| Tomatoes | Transplant outdoors | Jun 17 – May 26 |
| Peppers | Start seeds indoors | May 1 – Jun 1 |
| Peppers | Transplant outdoors | Jul 1 – Aug 1 |
| Eggplant | Start seeds indoors | May 18 – Jun 16 |
| Eggplant | Transplant outdoors | Jul 1 – Aug 1 |
| Cucumbers | Sow outdoors | Jul 1 – Jun 5 |
| Summer squash | Sow outdoors | Jun 17 – Aug 1 |
| Winter squash & pumpkins | Sow outdoors | Jul 1 – Aug 1 |
| Snap beans | Sow outdoors | Jun 17 – Jun 28 |
| Sweet corn | Sow outdoors | Jun 17 – May 26 |
| Watermelon & cantaloupe | Sow outdoors | Jul 1 – Aug 1 |
| Okra | Sow outdoors | Jun 24 – Jul 17 |
| Peas | Sow outdoors (spring) | May 1 – Jun 16 |
| Potatoes | Plant outdoors (spring) | May 1 – Jul 1 |
| Onions | Start seeds indoors (spring) | Mar 20 – Apr 16 |
| Onions | Transplant outdoors (spring) | May 18 – Jun 16 |
| Broccoli | Start seeds indoors (spring) | Apr 13 – May 17 |
| Broccoli | Transplant outdoors (spring) | May 18 – Jun 16 |
| Broccoli | Start seeds indoors (fall) | May 16 – May 26 |
| Broccoli | Transplant outdoors (fall) | Jun 15 – Jun 26 |
| Cabbage | Start seeds indoors (spring) | Apr 3 – May 1 |
| Cabbage | Transplant outdoors (spring) | May 1 – Jun 1 |
| Cabbage | Start seeds indoors (fall) | May 6 – Jun 5 |
| Cabbage | Transplant outdoors (fall) | Jun 5 – Jul 6 |
| Leaf lettuce | Sow outdoors (spring) | May 1 – Jul 17 |
| Leaf lettuce | Sow outdoors (fall) | Jun 5 – Jul 22 |
| Spinach | Sow outdoors (spring) | Apr 24 – Jun 7 |
| Spinach | Sow outdoors (fall) | Jun 22 – Jul 27 |
| Radishes | Sow outdoors (spring) | May 1 – Jun 21 |
| Radishes | Sow outdoors (fall) | Jun 5 – Aug 6 |
| Kale | Sow outdoors (spring) | May 18 – Jun 7 |
| Kale | Sow outdoors (fall) | May 29 – Jul 6 |
| Carrots | Sow outdoors (spring) | Jun 1 – Jul 17 |
| Carrots | Sow outdoors (fall) | May 6 – Jun 21 |
| Garlic | Plant outdoors (fall) | Sep 5 – Oct 6 |
Where these dates come from
ZIP code 59453 is matched to the NOAA station Judith Gap, MT, 6 km away, at 4,630 ft elevation (121 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Judith Gap, MT (used) | 4,630 ft | Jun 1 | Sep 15 |
| Judith Gap 13 E, MT | 4,791 ft | Jun 3 | Sep 15 |
| Harlowton 11Nw, MT | 4,954 ft | May 30 | Sep 20 |
| Harlowton, MT | 4,222 ft | May 23 | Sep 16 |
Frost dates near Judith Gap
- Buffalo, MT 59418 · last May 28, first Sep 20
- Harlowton, MT 59036 · last May 23, first Sep 16
- Shawmut, MT 59078 · last May 23, first Sep 16
- Moore, MT 59464 · last May 23, first Sep 21
- Hobson, MT 59452 · last May 28, first Sep 20
- Two Dot, MT 59085 · last May 23, first Sep 16
- Lewistown, MT 59457 · last May 23, first Sep 21
- Moccasin, MT 59462 · last May 28, first Sep 20
Frequently asked questions
- When is the last frost in Judith Gap, MT?
- For ZIP code 59453, the average last spring frost (32°F) is June 1, based on NOAA 1991-2020 climate normals for the Judith Gap, MT weather station. There is a 1-in-10 chance of a frost after June 16.
- When is the first frost in Judith Gap, MT?
- The average first fall frost (32°F) is September 15. There is a 1-in-10 chance of frost by August 31, so tender plants are at risk from that point on.
- How long is the growing season in 59453?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 104 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.