Frost dates for 59749Sheridan, MT
The average last spring frost in Sheridan is May 24 and the average first fall frost is September 22, giving a typical growing season of about 117 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 24
- Average first fall frost
- Sep 22
- Growing season
- 117 days
Safer after Jun 13 (1-in-10 risk)
Possible by Sep 6 (1-in-10 risk)
Last frost typically in 209 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 28 · Jun 12 · Jul 2 | Aug 27 · Sep 10 · Sep 24 | 87 days | 100% |
| Frost / freeze (32°F) | May 11 · May 24 · Jun 13 | Sep 6 · Sep 22 · Oct 6 | 117 days | 100% |
| Hard freeze (28°F) | Apr 28 · May 10 · May 23 | Sep 18 · Oct 3 · Oct 19 | 146 days | 100% |
Planting calendar for Sheridan
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 23 – Jun 29 |
| Tomatoes | Transplant outdoors | Jun 9 – Jun 2 |
| Peppers | Start seeds indoors | Apr 23 – May 24 |
| Peppers | Transplant outdoors | Jun 23 – Jul 24 |
| Eggplant | Start seeds indoors | May 10 – Jun 8 |
| Eggplant | Transplant outdoors | Jun 23 – Jul 24 |
| Cucumbers | Sow outdoors | Jun 23 – Jun 12 |
| Summer squash | Sow outdoors | Jun 9 – Jul 24 |
| Winter squash & pumpkins | Sow outdoors | Jun 23 – Jul 24 |
| Snap beans | Sow outdoors | Jun 9 – Jul 5 |
| Sweet corn | Sow outdoors | Jun 9 – Jun 2 |
| Watermelon & cantaloupe | Sow outdoors | Jun 23 – Jul 24 |
| Okra | Sow outdoors | Jun 16 – Jul 9 |
| Peas | Sow outdoors (spring) | Apr 23 – Jun 8 |
| Potatoes | Plant outdoors (spring) | Apr 23 – Jun 23 |
| Onions | Start seeds indoors (spring) | Mar 12 – Apr 8 |
| Onions | Transplant outdoors (spring) | May 10 – Jun 8 |
| Broccoli | Start seeds indoors (spring) | Apr 5 – May 9 |
| Broccoli | Transplant outdoors (spring) | May 10 – Jun 8 |
| Broccoli | Start seeds indoors (fall) | May 23 – Jun 2 |
| Broccoli | Transplant outdoors (fall) | Jun 22 – Jul 3 |
| Cabbage | Start seeds indoors (spring) | Mar 26 – Apr 23 |
| Cabbage | Transplant outdoors (spring) | Apr 23 – May 24 |
| Cabbage | Start seeds indoors (fall) | May 13 – Jun 12 |
| Cabbage | Transplant outdoors (fall) | Jun 12 – Jul 13 |
| Leaf lettuce | Sow outdoors (spring) | Apr 23 – Jul 9 |
| Leaf lettuce | Sow outdoors (fall) | Jun 12 – Jul 29 |
| Spinach | Sow outdoors (spring) | Apr 16 – May 30 |
| Spinach | Sow outdoors (fall) | Jun 29 – Aug 3 |
| Radishes | Sow outdoors (spring) | Apr 23 – Jun 13 |
| Radishes | Sow outdoors (fall) | Jun 12 – Aug 13 |
| Kale | Sow outdoors (spring) | May 10 – May 30 |
| Kale | Sow outdoors (fall) | Jun 5 – Jul 13 |
| Carrots | Sow outdoors (spring) | May 24 – Jul 9 |
| Carrots | Sow outdoors (fall) | May 13 – Jun 28 |
| Garlic | Plant outdoors (fall) | Sep 12 – Oct 13 |
Where these dates come from
ZIP code 59749 is matched to the NOAA station Laurin 2Ne, MT, 8.6 km away, at 5,198 ft elevation (110 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Laurin 2Ne, MT (used) | 5,198 ft | May 24 | Sep 22 |
| Twin Bridges, MT | 4,625 ft | Jun 8 | Sep 2 |
| Virginia City, MT | 5,773 ft | Jun 4 | Sep 18 |
| Dillon Ap, MT | 5,200 ft | Jun 2 | Sep 13 |
Frost dates near Sheridan
- Twin Bridges, MT 59754 · last Jun 8, first Sep 2
- Virginia City, MT 59755 · last Jun 4, first Sep 18
- Alder, MT 59710 · last Jun 6, first Sep 14
- Mc Allister, MT 59740 · last Jun 16, first Sep 4
- Silver Star, MT 59751 · last Jun 8, first Sep 2
- Pony, MT 59747 · last Jun 4, first Sep 18
- Ennis, MT 59729 · last Jun 16, first Sep 4
- Norris, MT 59745 · last Apr 30, first Oct 10
Frequently asked questions
- When is the last frost in Sheridan, MT?
- For ZIP code 59749, the average last spring frost (32°F) is May 24, based on NOAA 1991-2020 climate normals for the Laurin 2Ne, MT weather station. There is a 1-in-10 chance of a frost after June 13.
- When is the first frost in Sheridan, MT?
- The average first fall frost (32°F) is September 22. There is a 1-in-10 chance of frost by September 6, so tender plants are at risk from that point on.
- How long is the growing season in 59749?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 117 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.