Frost dates for 59015Broadview, MT
The average last spring frost in Broadview is May 22 and the average first fall frost is September 15, giving a typical growing season of about 114 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 22
- Average first fall frost
- Sep 15
- Growing season
- 114 days
Safer after Jun 4 (1-in-10 risk)
Possible by Aug 31 (1-in-10 risk)
Last frost typically in 200 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 5 · Jun 20 | Aug 22 · Sep 4 · Sep 15 | 88 days | 100% |
| Frost / freeze (32°F) | May 11 · May 22 · Jun 4 | Aug 31 · Sep 15 · Sep 29 | 114 days | 100% |
| Hard freeze (28°F) | Apr 30 · May 11 · May 22 | Sep 11 · Sep 26 · Oct 10 | 138 days | 100% |
Planting calendar for Broadview
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 21 – Jun 27 |
| Tomatoes | Transplant outdoors | Jun 7 – May 26 |
| Peppers | Start seeds indoors | Apr 21 – May 22 |
| Peppers | Transplant outdoors | Jun 21 – Jul 22 |
| Eggplant | Start seeds indoors | May 8 – Jun 6 |
| Eggplant | Transplant outdoors | Jun 21 – Jul 22 |
| Cucumbers | Sow outdoors | Jun 21 – Jun 5 |
| Summer squash | Sow outdoors | Jun 7 – Jul 22 |
| Winter squash & pumpkins | Sow outdoors | Jun 21 – Jul 22 |
| Snap beans | Sow outdoors | Jun 7 – Jun 28 |
| Sweet corn | Sow outdoors | Jun 7 – May 26 |
| Watermelon & cantaloupe | Sow outdoors | Jun 21 – Jul 22 |
| Okra | Sow outdoors | Jun 14 – Jul 7 |
| Peas | Sow outdoors (spring) | Apr 21 – Jun 6 |
| Potatoes | Plant outdoors (spring) | Apr 21 – Jun 21 |
| Onions | Start seeds indoors (spring) | Mar 10 – Apr 6 |
| Onions | Transplant outdoors (spring) | May 8 – Jun 6 |
| Broccoli | Start seeds indoors (spring) | Apr 3 – May 7 |
| Broccoli | Transplant outdoors (spring) | May 8 – Jun 6 |
| Broccoli | Start seeds indoors (fall) | May 16 – May 26 |
| Broccoli | Transplant outdoors (fall) | Jun 15 – Jun 26 |
| Cabbage | Start seeds indoors (spring) | Mar 24 – Apr 21 |
| Cabbage | Transplant outdoors (spring) | Apr 21 – May 22 |
| Cabbage | Start seeds indoors (fall) | May 6 – Jun 5 |
| Cabbage | Transplant outdoors (fall) | Jun 5 – Jul 6 |
| Leaf lettuce | Sow outdoors (spring) | Apr 21 – Jul 7 |
| Leaf lettuce | Sow outdoors (fall) | Jun 5 – Jul 22 |
| Spinach | Sow outdoors (spring) | Apr 14 – May 28 |
| Spinach | Sow outdoors (fall) | Jun 22 – Jul 27 |
| Radishes | Sow outdoors (spring) | Apr 21 – Jun 11 |
| Radishes | Sow outdoors (fall) | Jun 5 – Aug 6 |
| Kale | Sow outdoors (spring) | May 8 – May 28 |
| Kale | Sow outdoors (fall) | May 29 – Jul 6 |
| Carrots | Sow outdoors (spring) | May 22 – Jul 7 |
| Carrots | Sow outdoors (fall) | May 6 – Jun 21 |
| Garlic | Plant outdoors (fall) | Sep 5 – Oct 6 |
Where these dates come from
ZIP code 59015 is matched to the NOAA station Roundup 15 Sw, MT, 27.6 km away, at 3,386 ft elevation (357 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Roundup 15 Sw, MT (used) | 3,386 ft | May 22 | Sep 15 |
| Rapelje, MT | 4,068 ft | May 24 | Sep 21 |
| Billings Logan Intl Ap, MT | 3,581 ft | May 4 | Oct 7 |
| Billings Wfo, MT | 3,185 ft | May 5 | Oct 3 |
Frost dates near Broadview
- Acton, MT 59002 · last May 4, first Oct 7
- Billings, MT 59105 · last May 4, first Oct 7
- Molt, MT 59057 · last May 24, first Sep 21
- Lavina, MT 59046 · last May 17, first Sep 23
- Rapelje, MT 59067 · last May 24, first Sep 21
- Shepherd, MT 59079 · last May 12, first Sep 25
- Ryegate, MT 59074 · last May 17, first Sep 23
- Roundup, MT 59072 · last May 20, first Sep 21
Frequently asked questions
- When is the last frost in Broadview, MT?
- For ZIP code 59015, the average last spring frost (32°F) is May 22, based on NOAA 1991-2020 climate normals for the Roundup 15 Sw, MT weather station. There is a 1-in-10 chance of a frost after June 4.
- When is the first frost in Broadview, MT?
- The average first fall frost (32°F) is September 15. There is a 1-in-10 chance of frost by August 31, so tender plants are at risk from that point on.
- How long is the growing season in 59015?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 114 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.