Frost dates for 59833Florence, MT
The average last spring frost in Florence is May 22 and the average first fall frost is September 19, giving a typical growing season of about 115 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 22
- Average first fall frost
- Sep 19
- Growing season
- 115 days
Safer after Jun 13 (1-in-10 risk)
Possible by Sep 3 (1-in-10 risk)
Last frost typically in 207 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) | — | — | 77 days | 100% |
| Frost / freeze (32°F) | May 7 · May 22 · Jun 13 | Sep 3 · Sep 19 · Oct 2 | 115 days | 100% |
| Hard freeze (28°F) | Apr 23 · May 5 · May 19 | Sep 15 · Oct 1 · Oct 15 | 147 days | 100% |
Planting calendar for Florence
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 30 |
| 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 9 |
| Summer squash | Sow outdoors | Jun 7 – Jul 22 |
| Winter squash & pumpkins | Sow outdoors | Jun 21 – Jul 22 |
| Snap beans | Sow outdoors | Jun 7 – Jul 2 |
| Sweet corn | Sow outdoors | Jun 7 – May 30 |
| 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 20 – May 30 |
| Broccoli | Transplant outdoors (fall) | Jun 19 – Jun 30 |
| Cabbage | Start seeds indoors (spring) | Mar 24 – Apr 21 |
| Cabbage | Transplant outdoors (spring) | Apr 21 – May 22 |
| Cabbage | Start seeds indoors (fall) | May 10 – Jun 9 |
| Cabbage | Transplant outdoors (fall) | Jun 9 – Jul 10 |
| Leaf lettuce | Sow outdoors (spring) | Apr 21 – Jul 7 |
| Leaf lettuce | Sow outdoors (fall) | Jun 9 – Jul 26 |
| Spinach | Sow outdoors (spring) | Apr 14 – May 28 |
| Spinach | Sow outdoors (fall) | Jun 26 – Jul 31 |
| Radishes | Sow outdoors (spring) | Apr 21 – Jun 11 |
| Radishes | Sow outdoors (fall) | Jun 9 – Aug 10 |
| Kale | Sow outdoors (spring) | May 8 – May 28 |
| Kale | Sow outdoors (fall) | Jun 2 – Jul 10 |
| Carrots | Sow outdoors (spring) | May 22 – Jul 7 |
| Carrots | Sow outdoors (fall) | May 10 – Jun 25 |
| Garlic | Plant outdoors (fall) | Sep 9 – Oct 10 |
Where these dates come from
ZIP code 59833 is matched to the NOAA station Stevensville, MT, 13.1 km away, at 3,375 ft elevation (19 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Stevensville, MT (used) | 3,375 ft | May 22 | Sep 19 |
| Missoula 2 Ne, MT | 3,420 ft | May 10 | Oct 1 |
| Missoula Intl Ap, MT | 3,192 ft | May 16 | Sep 26 |
| Missoula 6 Nw Wfo, MT | 3,197 ft | May 6 | Oct 4 |
Frost dates near Florence
- Stevensville, MT 59870 · last May 22, first Sep 19
- Lolo, MT 59847 · last May 16, first Sep 26
- Missoula, MT 59803 · last May 10, first Oct 1
- Victor, MT 59875 · last May 23, first Sep 21
- Milltown, MT 59851 · last May 10, first Oct 1
- Bonner, MT 59823 · last May 10, first Oct 1
- Clinton, MT 59825 · last —, first —
- Pinesdale, MT 59841 · last May 23, first Sep 21
Frequently asked questions
- When is the last frost in Florence, MT?
- For ZIP code 59833, the average last spring frost (32°F) is May 22, based on NOAA 1991-2020 climate normals for the Stevensville, MT weather station. There is a 1-in-10 chance of a frost after June 13.
- When is the first frost in Florence, MT?
- The average first fall frost (32°F) is September 19. 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 59833?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 115 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.