Frost dates for 59451Hilger, MT
The average last spring frost in Hilger is May 23 and the average first fall frost is September 21, giving a typical growing season of about 119 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 23
- Average first fall frost
- Sep 21
- Growing season
- 119 days
Safer after Jun 8 (1-in-10 risk)
Possible by Sep 8 (1-in-10 risk)
Last frost typically in 201 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 26 · Jun 11 · Jul 3 | Aug 24 · Sep 8 · Sep 21 | 86 days | 100% |
| Frost / freeze (32°F) | May 11 · May 23 · Jun 8 | Sep 8 · Sep 21 · Oct 3 | 119 days | 100% |
| Hard freeze (28°F) | Apr 27 · May 9 · May 24 | Sep 18 · Oct 1 · Oct 15 | 145 days | 100% |
Planting calendar for Hilger
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 22 – Jun 28 |
| Tomatoes | Transplant outdoors | Jun 8 – Jun 1 |
| Peppers | Start seeds indoors | Apr 22 – May 23 |
| Peppers | Transplant outdoors | Jun 22 – Jul 23 |
| Eggplant | Start seeds indoors | May 9 – Jun 7 |
| Eggplant | Transplant outdoors | Jun 22 – Jul 23 |
| Cucumbers | Sow outdoors | Jun 22 – Jun 11 |
| Summer squash | Sow outdoors | Jun 8 – Jul 23 |
| Winter squash & pumpkins | Sow outdoors | Jun 22 – Jul 23 |
| Snap beans | Sow outdoors | Jun 8 – Jul 4 |
| Sweet corn | Sow outdoors | Jun 8 – Jun 1 |
| Watermelon & cantaloupe | Sow outdoors | Jun 22 – Jul 23 |
| Okra | Sow outdoors | Jun 15 – Jul 8 |
| Peas | Sow outdoors (spring) | Apr 22 – Jun 7 |
| Potatoes | Plant outdoors (spring) | Apr 22 – Jun 22 |
| Onions | Start seeds indoors (spring) | Mar 11 – Apr 7 |
| Onions | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (spring) | Apr 4 – May 8 |
| Broccoli | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (fall) | May 22 – Jun 1 |
| Broccoli | Transplant outdoors (fall) | Jun 21 – Jul 2 |
| Cabbage | Start seeds indoors (spring) | Mar 25 – Apr 22 |
| Cabbage | Transplant outdoors (spring) | Apr 22 – May 23 |
| Cabbage | Start seeds indoors (fall) | May 12 – Jun 11 |
| Cabbage | Transplant outdoors (fall) | Jun 11 – Jul 12 |
| Leaf lettuce | Sow outdoors (spring) | Apr 22 – Jul 8 |
| Leaf lettuce | Sow outdoors (fall) | Jun 11 – Jul 28 |
| Spinach | Sow outdoors (spring) | Apr 15 – May 29 |
| Spinach | Sow outdoors (fall) | Jun 28 – Aug 2 |
| Radishes | Sow outdoors (spring) | Apr 22 – Jun 12 |
| Radishes | Sow outdoors (fall) | Jun 11 – Aug 12 |
| Kale | Sow outdoors (spring) | May 9 – May 29 |
| Kale | Sow outdoors (fall) | Jun 4 – Jul 12 |
| Carrots | Sow outdoors (spring) | May 23 – Jul 8 |
| Carrots | Sow outdoors (fall) | May 12 – Jun 27 |
| Garlic | Plant outdoors (fall) | Sep 11 – Oct 12 |
Where these dates come from
ZIP code 59451 is matched to the NOAA station Lewistown Muni Ap, MT, 23.9 km away, at 4,145 ft elevation (73 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Lewistown Muni Ap, MT (used) | 4,145 ft | May 23 | Sep 21 |
| Lewistown, MT | 3,911 ft | May 14 | Sep 28 |
| Lewistown 11Ese, MT | 5,028 ft | May 19 | Sep 25 |
| Winifred, MT | 3,243 ft | May 16 | Sep 23 |
Frost dates near Hilger
- Lewistown, MT 59457 · last May 23, first Sep 21
- Forest Grove, MT 59441 · last May 23, first Sep 21
- Roy, MT 59471 · last May 14, first Sep 24
- Denton, MT 59430 · last Jun 1, first Sep 11
- Moore, MT 59464 · last May 23, first Sep 21
- Moccasin, MT 59462 · last May 28, first Sep 20
- Winifred, MT 59489 · last May 16, first Sep 23
- Grass Range, MT 59032 · last May 20, first Sep 24
Frequently asked questions
- When is the last frost in Hilger, MT?
- For ZIP code 59451, the average last spring frost (32°F) is May 23, based on NOAA 1991-2020 climate normals for the Lewistown Muni Ap, MT weather station. There is a 1-in-10 chance of a frost after June 8.
- When is the first frost in Hilger, MT?
- The average first fall frost (32°F) is September 21. There is a 1-in-10 chance of frost by September 8, so tender plants are at risk from that point on.
- How long is the growing season in 59451?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 119 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.