Frost dates for 59913Coram, MT
The average last spring frost in Coram is May 18 and the average first fall frost is September 20, giving a typical growing season of about 124 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 18
- Average first fall frost
- Sep 20
- Growing season
- 124 days
Safer after Jun 4 (1-in-10 risk)
Possible by Sep 3 (1-in-10 risk)
Last frost typically in 199 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 23 · Jun 8 · Jul 1 | Aug 19 · Sep 4 · Sep 20 | 85 days | 100% |
| Frost / freeze (32°F) | May 6 · May 18 · Jun 4 | Sep 3 · Sep 20 · Oct 4 | 124 days | 100% |
| Hard freeze (28°F) | Apr 18 · May 1 · May 15 | Sep 20 · Oct 4 · Oct 21 | 155 days | 100% |
Planting calendar for Coram
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 17 – Jun 23 |
| Tomatoes | Transplant outdoors | Jun 3 – May 31 |
| Peppers | Start seeds indoors | Apr 17 – May 18 |
| Peppers | Transplant outdoors | Jun 17 – Jul 18 |
| Eggplant | Start seeds indoors | May 4 – Jun 2 |
| Eggplant | Transplant outdoors | Jun 17 – Jul 18 |
| Cucumbers | Sow outdoors | Jun 17 – Jun 10 |
| Summer squash | Sow outdoors | Jun 3 – Jul 18 |
| Winter squash & pumpkins | Sow outdoors | Jun 17 – Jul 18 |
| Snap beans | Sow outdoors | Jun 3 – Jul 3 |
| Sweet corn | Sow outdoors | Jun 3 – May 31 |
| Watermelon & cantaloupe | Sow outdoors | Jun 17 – Jul 18 |
| Okra | Sow outdoors | Jun 10 – Jul 3 |
| Peas | Sow outdoors (spring) | Apr 17 – Jun 2 |
| Potatoes | Plant outdoors (spring) | Apr 17 – Jun 17 |
| Onions | Start seeds indoors (spring) | Mar 6 – Apr 2 |
| Onions | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (spring) | Mar 30 – May 3 |
| Broccoli | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (fall) | May 21 – May 31 |
| Broccoli | Transplant outdoors (fall) | Jun 20 – Jul 1 |
| Cabbage | Start seeds indoors (spring) | Mar 20 – Apr 17 |
| Cabbage | Transplant outdoors (spring) | Apr 17 – May 18 |
| Cabbage | Start seeds indoors (fall) | May 11 – Jun 10 |
| Cabbage | Transplant outdoors (fall) | Jun 10 – Jul 11 |
| Leaf lettuce | Sow outdoors (spring) | Apr 17 – Jul 3 |
| Leaf lettuce | Sow outdoors (fall) | Jun 10 – Jul 27 |
| Spinach | Sow outdoors (spring) | Apr 10 – May 24 |
| Spinach | Sow outdoors (fall) | Jun 27 – Aug 1 |
| Radishes | Sow outdoors (spring) | Apr 17 – Jun 7 |
| Radishes | Sow outdoors (fall) | Jun 10 – Aug 11 |
| Kale | Sow outdoors (spring) | May 4 – May 24 |
| Kale | Sow outdoors (fall) | Jun 3 – Jul 11 |
| Carrots | Sow outdoors (spring) | May 18 – Jul 3 |
| Carrots | Sow outdoors (fall) | May 11 – Jun 26 |
| Garlic | Plant outdoors (fall) | Sep 10 – Oct 11 |
Where these dates come from
ZIP code 59913 is matched to the NOAA station W Glacier, MT, 9.1 km away, at 3,148 ft elevation (38 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| W Glacier, MT (used) | 3,148 ft | May 18 | Sep 20 |
| Hungry Horse Dam, MT | 3,160 ft | May 9 | Oct 1 |
| Kalispell Glacier Ap, MT | 2,957 ft | May 31 | Sep 10 |
| Whitefish, MT | 3,100 ft | May 16 | Sep 25 |
Frost dates near Coram
- Martin City, MT 59926 · last May 9, first Oct 1
- Hungry Horse, MT 59919 · last May 9, first Oct 1
- West Glacier, MT 59936 · last May 18, first Sep 20
- Columbia Falls, MT 59912 · last May 31, first Sep 10
- Lake Mc Donald, MT 59921 · last May 9, first Oct 1
- Whitefish, MT 59937 · last May 16, first Sep 25
- Kalispell, MT 59904 · last May 31, first Sep 10
- Essex, MT 59916 · last May 9, first Oct 1
Frequently asked questions
- When is the last frost in Coram, MT?
- For ZIP code 59913, the average last spring frost (32°F) is May 18, based on NOAA 1991-2020 climate normals for the W Glacier, MT weather station. There is a 1-in-10 chance of a frost after June 4.
- When is the first frost in Coram, MT?
- The average first fall frost (32°F) is September 20. There is a 1-in-10 chance of frost by September 3, so tender plants are at risk from that point on.
- How long is the growing season in 59913?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 124 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.