Frost dates for 59544Whitewater, MT
The average last spring frost in Whitewater is May 15 and the average first fall frost is September 23, giving a typical growing season of about 130 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 15
- Average first fall frost
- Sep 23
- Growing season
- 130 days
Safer after May 26 (1-in-10 risk)
Possible by Sep 11 (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 13 · May 24 · Jun 4 | Sep 2 · Sep 15 · Sep 25 | 112 days | 100% |
| Frost / freeze (32°F) | May 3 · May 15 · May 26 | Sep 11 · Sep 23 · Oct 4 | 130 days | 100% |
| Hard freeze (28°F) | Apr 23 · May 6 · May 17 | Sep 19 · Oct 1 · Oct 15 | 148 days | 100% |
Planting calendar for Whitewater
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 14 – Jun 20 |
| Tomatoes | Transplant outdoors | May 31 – Jun 3 |
| Peppers | Start seeds indoors | Apr 14 – May 15 |
| Peppers | Transplant outdoors | Jun 14 – Jul 15 |
| Eggplant | Start seeds indoors | May 1 – May 30 |
| Eggplant | Transplant outdoors | Jun 14 – Jul 15 |
| Cucumbers | Sow outdoors | Jun 14 – Jun 13 |
| Summer squash | Sow outdoors | May 31 – Jul 15 |
| Winter squash & pumpkins | Sow outdoors | Jun 14 – Jul 15 |
| Snap beans | Sow outdoors | May 31 – Jul 6 |
| Sweet corn | Sow outdoors | May 31 – Jun 3 |
| Watermelon & cantaloupe | Sow outdoors | Jun 14 – Jul 15 |
| Okra | Sow outdoors | Jun 7 – Jun 30 |
| Peas | Sow outdoors (spring) | Apr 14 – May 30 |
| Potatoes | Plant outdoors (spring) | Apr 14 – Jun 14 |
| Onions | Start seeds indoors (spring) | Mar 3 – Mar 30 |
| Onions | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (spring) | Mar 27 – Apr 30 |
| Broccoli | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (fall) | May 24 – Jun 3 |
| Broccoli | Transplant outdoors (fall) | Jun 23 – Jul 4 |
| Cabbage | Start seeds indoors (spring) | Mar 17 – Apr 14 |
| Cabbage | Transplant outdoors (spring) | Apr 14 – May 15 |
| Cabbage | Start seeds indoors (fall) | May 14 – Jun 13 |
| Cabbage | Transplant outdoors (fall) | Jun 13 – Jul 14 |
| Leaf lettuce | Sow outdoors (spring) | Apr 14 – Jun 30 |
| Leaf lettuce | Sow outdoors (fall) | Jun 13 – Jul 30 |
| Spinach | Sow outdoors (spring) | Apr 7 – May 21 |
| Spinach | Sow outdoors (fall) | Jun 30 – Aug 4 |
| Radishes | Sow outdoors (spring) | Apr 14 – Jun 4 |
| Radishes | Sow outdoors (fall) | Jun 13 – Aug 14 |
| Kale | Sow outdoors (spring) | May 1 – May 21 |
| Kale | Sow outdoors (fall) | Jun 6 – Jul 14 |
| Carrots | Sow outdoors (spring) | May 15 – Jun 30 |
| Carrots | Sow outdoors (fall) | May 14 – Jun 29 |
| Garlic | Plant outdoors (fall) | Sep 13 – Oct 14 |
Where these dates come from
ZIP code 59544 is matched to the NOAA station Saco 1 Nnw, MT, 38.4 km away, at 2,185 ft elevation (138 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Saco 1 Nnw, MT (used) | 2,185 ft | May 15 | Sep 23 |
| Port Of Morgan, MT | 2,830 ft | May 19 | Sep 22 |
| Malta 7 E, MT | 2,231 ft | May 7 | Sep 28 |
| Malta, MT | 2,262 ft | May 10 | Sep 29 |
Frost dates near Whitewater
- Loring, MT 59537 · last May 19, first Sep 22
- Saco, MT 59261 · last May 15, first Sep 23
- Malta, MT 59538 · last May 10, first Sep 29
- Turner, MT 59542 · last May 19, first Sep 21
- Hinsdale, MT 59241 · last May 15, first Sep 23
- Dodson, MT 59524 · last May 10, first Sep 29
- Vandalia, MT 59273 · last May 3, first Oct 1
- Hogeland, MT 59529 · last May 19, first Sep 21
Frequently asked questions
- When is the last frost in Whitewater, MT?
- For ZIP code 59544, the average last spring frost (32°F) is May 15, based on NOAA 1991-2020 climate normals for the Saco 1 Nnw, MT weather station. There is a 1-in-10 chance of a frost after May 26.
- When is the first frost in Whitewater, MT?
- The average first fall frost (32°F) is September 23. There is a 1-in-10 chance of frost by September 11, so tender plants are at risk from that point on.
- How long is the growing season in 59544?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 130 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.