Frost dates for 59102Billings, MT
The average last spring frost in Billings is May 5 and the average first fall frost is October 3, giving a typical growing season of about 149 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 5
- Average first fall frost
- Oct 3
- Growing season
- 149 days
Safer after May 21 (1-in-10 risk)
Possible by Sep 20 (1-in-10 risk)
Last frost typically in 183 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 6 · May 19 · Jun 2 | Sep 9 · Sep 23 · Oct 5 | 125 days | 100% |
| Frost / freeze (32°F) | Apr 23 · May 5 · May 21 | Sep 20 · Oct 3 · Oct 17 | 149 days | 100% |
| Hard freeze (28°F) | Apr 7 · Apr 23 · May 6 | Sep 29 · Oct 14 · Oct 27 | 172 days | 100% |
Planting calendar for Billings
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 4 – Jun 10 |
| Tomatoes | Transplant outdoors | May 21 – Jun 13 |
| Peppers | Start seeds indoors | Apr 4 – May 5 |
| Peppers | Transplant outdoors | Jun 4 – Jul 5 |
| Eggplant | Start seeds indoors | Apr 21 – May 20 |
| Eggplant | Transplant outdoors | Jun 4 – Jul 5 |
| Cucumbers | Sow outdoors | Jun 4 – Jun 23 |
| Summer squash | Sow outdoors | May 21 – Jul 5 |
| Winter squash & pumpkins | Sow outdoors | Jun 4 – Jul 5 |
| Snap beans | Sow outdoors | May 21 – Jul 16 |
| Sweet corn | Sow outdoors | May 21 – Jun 13 |
| Watermelon & cantaloupe | Sow outdoors | Jun 4 – Jul 5 |
| Okra | Sow outdoors | May 28 – Jun 20 |
| Peas | Sow outdoors (spring) | Apr 4 – May 20 |
| Potatoes | Plant outdoors (spring) | Apr 4 – Jun 4 |
| Onions | Start seeds indoors (spring) | Feb 21 – Mar 20 |
| Onions | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (spring) | Mar 17 – Apr 20 |
| Broccoli | Transplant outdoors (spring) | Apr 21 – May 20 |
| Broccoli | Start seeds indoors (fall) | Jun 3 – Jun 13 |
| Broccoli | Transplant outdoors (fall) | Jul 3 – Jul 14 |
| Cabbage | Start seeds indoors (spring) | Mar 7 – Apr 4 |
| Cabbage | Transplant outdoors (spring) | Apr 4 – May 5 |
| Cabbage | Start seeds indoors (fall) | May 24 – Jun 23 |
| Cabbage | Transplant outdoors (fall) | Jun 23 – Jul 24 |
| Leaf lettuce | Sow outdoors (spring) | Apr 4 – Jun 20 |
| Leaf lettuce | Sow outdoors (fall) | Jun 23 – Aug 9 |
| Spinach | Sow outdoors (spring) | Mar 28 – May 11 |
| Spinach | Sow outdoors (fall) | Jul 10 – Aug 14 |
| Radishes | Sow outdoors (spring) | Apr 4 – May 25 |
| Radishes | Sow outdoors (fall) | Jun 23 – Aug 24 |
| Kale | Sow outdoors (spring) | Apr 21 – May 11 |
| Kale | Sow outdoors (fall) | Jun 16 – Jul 24 |
| Carrots | Sow outdoors (spring) | May 5 – Jun 20 |
| Carrots | Sow outdoors (fall) | May 24 – Jul 9 |
| Garlic | Plant outdoors (fall) | Sep 23 – Oct 24 |
Where these dates come from
ZIP code 59102 is matched to the NOAA station Billings Wfo, MT, 3.5 km away, at 3,185 ft elevation (37 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Billings Wfo, MT (used) | 3,185 ft | May 5 | Oct 3 |
| Billings Logan Intl Ap, MT | 3,581 ft | May 4 | Oct 7 |
| Billings Wtp, MT | 3,097 ft | May 10 | Oct 1 |
| Huntley Exp Stn, MT | 3,034 ft | May 12 | Sep 25 |
Frost dates near Billings
- Billings, MT 59103 · last May 10, first Oct 1
- Acton, MT 59002 · last May 4, first Oct 7
- Laurel, MT 59044 · last May 5, first Oct 3
- Huntley, MT 59037 · last May 12, first Sep 25
- Shepherd, MT 59079 · last May 12, first Sep 25
- Park City, MT 59063 · last May 27, first Sep 14
- Molt, MT 59057 · last May 24, first Sep 21
- Broadview, MT 59015 · last May 22, first Sep 15
Frequently asked questions
- When is the last frost in Billings, MT?
- For ZIP code 59102, the average last spring frost (32°F) is May 5, based on NOAA 1991-2020 climate normals for the Billings Wfo, MT weather station. There is a 1-in-10 chance of a frost after May 21.
- When is the first frost in Billings, MT?
- The average first fall frost (32°F) is October 3. There is a 1-in-10 chance of frost by September 20, so tender plants are at risk from that point on.
- How long is the growing season in 59102?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 149 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.