Frost dates for 59250Opheim, MT
The average last spring frost in Opheim is June 1 and the average first fall frost is September 7, giving a typical growing season of about 99 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 1
- Average first fall frost
- Sep 7
- Growing season
- 99 days
Safer after Jun 18 (1-in-10 risk)
Possible by Aug 24 (1-in-10 risk)
Last frost typically in 217 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) | — | — | 65 days | 100% |
| Frost / freeze (32°F) | May 20 · Jun 1 · Jun 18 | Aug 24 · Sep 7 · Sep 21 | 99 days | 100% |
| Hard freeze (28°F) | May 9 · May 21 · Jun 4 | Sep 5 · Sep 19 · Oct 1 | 119 days | 100% |
Planting calendar for Opheim
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 18 |
| 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 – May 28 |
| Summer squash | Sow outdoors | Jun 17 – Aug 1 |
| Winter squash & pumpkins | Sow outdoors | Jul 1 – Aug 1 |
| Snap beans | Sow outdoors | Jun 17 – Jun 20 |
| Sweet corn | Sow outdoors | Jun 17 – May 18 |
| 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 8 – May 18 |
| Broccoli | Transplant outdoors (fall) | Jun 7 – Jun 18 |
| Cabbage | Start seeds indoors (spring) | Apr 3 – May 1 |
| Cabbage | Transplant outdoors (spring) | May 1 – Jun 1 |
| Cabbage | Start seeds indoors (fall) | Apr 28 – May 28 |
| Cabbage | Transplant outdoors (fall) | May 28 – Jun 28 |
| Leaf lettuce | Sow outdoors (spring) | May 1 – Jul 17 |
| Leaf lettuce | Sow outdoors (fall) | May 28 – Jul 14 |
| Spinach | Sow outdoors (spring) | Apr 24 – Jun 7 |
| Spinach | Sow outdoors (fall) | Jun 14 – Jul 19 |
| Radishes | Sow outdoors (spring) | May 1 – Jun 21 |
| Radishes | Sow outdoors (fall) | May 28 – Jul 29 |
| Kale | Sow outdoors (spring) | May 18 – Jun 7 |
| Kale | Sow outdoors (fall) | May 21 – Jun 28 |
| Carrots | Sow outdoors (spring) | Jun 1 – Jul 17 |
| Carrots | Sow outdoors (fall) | Apr 28 – Jun 13 |
| Garlic | Plant outdoors (fall) | Aug 28 – Sep 28 |
Where these dates come from
ZIP code 59250 is matched to the NOAA station Opheim 10 N, MT, 14.3 km away, at 2,878 ft elevation (331 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Opheim 10 N, MT (used) | 2,878 ft | Jun 1 | Sep 7 |
| Opheim 12 Sse, MT | 2,936 ft | Jun 5 | Sep 2 |
| St Marie, MT | 2,756 ft | May 13 | Sep 27 |
| Scobey 4 Nw, MT | 2,390 ft | May 28 | Sep 6 |
Frost dates near Opheim
- Glentana, MT 59240 · last Jun 5, first Sep 2
- Richland, MT 59260 · last Jun 5, first Sep 2
- Larslan, MT 59244 · last Jun 5, first Sep 2
- Peerless, MT 59253 · last Jun 5, first Sep 2
- Saint Marie, MT 59231 · last May 13, first Sep 27
- Frazer, MT 59225 · last May 13, first Sep 27
- Vandalia, MT 59273 · last May 3, first Oct 1
- Scobey, MT 59263 · last May 28, first Sep 6
Frequently asked questions
- When is the last frost in Opheim, MT?
- For ZIP code 59250, the average last spring frost (32°F) is June 1, based on NOAA 1991-2020 climate normals for the Opheim 10 N, MT weather station. There is a 1-in-10 chance of a frost after June 18.
- When is the first frost in Opheim, MT?
- The average first fall frost (32°F) is September 7. There is a 1-in-10 chance of frost by August 24, so tender plants are at risk from that point on.
- How long is the growing season in 59250?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 99 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.