Frost dates for 54512Boulder Junction, WI
The average last spring frost in Boulder Junction is May 25 and the average first fall frost is September 21, giving a typical growing season of about 117 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 25
- Average first fall frost
- Sep 21
- Growing season
- 117 days
Safer after Jun 9 (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) | — | — | 91 days | 100% |
| Frost / freeze (32°F) | May 8 · May 25 · Jun 9 | Sep 3 · Sep 21 · Oct 6 | 117 days | 100% |
| Hard freeze (28°F) | Apr 27 · May 11 · May 28 | Sep 14 · Oct 1 · Oct 15 | 142 days | 100% |
Planting calendar for Boulder Junction
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 24 – Jun 30 |
| Tomatoes | Transplant outdoors | Jun 10 – Jun 1 |
| Peppers | Start seeds indoors | Apr 24 – May 25 |
| Peppers | Transplant outdoors | Jun 24 – Jul 25 |
| Eggplant | Start seeds indoors | May 11 – Jun 9 |
| Eggplant | Transplant outdoors | Jun 24 – Jul 25 |
| Cucumbers | Sow outdoors | Jun 24 – Jun 11 |
| Summer squash | Sow outdoors | Jun 10 – Jul 25 |
| Winter squash & pumpkins | Sow outdoors | Jun 24 – Jul 25 |
| Snap beans | Sow outdoors | Jun 10 – Jul 4 |
| Sweet corn | Sow outdoors | Jun 10 – Jun 1 |
| Watermelon & cantaloupe | Sow outdoors | Jun 24 – Jul 25 |
| Okra | Sow outdoors | Jun 17 – Jul 10 |
| Peas | Sow outdoors (spring) | Apr 24 – Jun 9 |
| Potatoes | Plant outdoors (spring) | Apr 24 – Jun 24 |
| Onions | Start seeds indoors (spring) | Mar 13 – Apr 9 |
| Onions | Transplant outdoors (spring) | May 11 – Jun 9 |
| Broccoli | Start seeds indoors (spring) | Apr 6 – May 10 |
| Broccoli | Transplant outdoors (spring) | May 11 – Jun 9 |
| Broccoli | Start seeds indoors (fall) | May 22 – Jun 1 |
| Broccoli | Transplant outdoors (fall) | Jun 21 – Jul 2 |
| Cabbage | Start seeds indoors (spring) | Mar 27 – Apr 24 |
| Cabbage | Transplant outdoors (spring) | Apr 24 – May 25 |
| Cabbage | Start seeds indoors (fall) | May 12 – Jun 11 |
| Cabbage | Transplant outdoors (fall) | Jun 11 – Jul 12 |
| Leaf lettuce | Sow outdoors (spring) | Apr 24 – Jul 10 |
| Leaf lettuce | Sow outdoors (fall) | Jun 11 – Jul 28 |
| Spinach | Sow outdoors (spring) | Apr 17 – May 31 |
| Spinach | Sow outdoors (fall) | Jun 28 – Aug 2 |
| Radishes | Sow outdoors (spring) | Apr 24 – Jun 14 |
| Radishes | Sow outdoors (fall) | Jun 11 – Aug 12 |
| Kale | Sow outdoors (spring) | May 11 – May 31 |
| Kale | Sow outdoors (fall) | Jun 4 – Jul 12 |
| Carrots | Sow outdoors (spring) | May 25 – Jul 10 |
| Carrots | Sow outdoors (fall) | May 12 – Jun 27 |
| Garlic | Plant outdoors (fall) | Sep 11 – Oct 12 |
Where these dates come from
ZIP code 54512 is matched to the NOAA station Rest Lake, WI, 18.9 km away, at 1,612 ft elevation (42 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Rest Lake, WI (used) | 1,612 ft | May 25 | Sep 21 |
| St Germain, WI | 1,643 ft | May 19 | Oct 3 |
| Minocqua, WI | 1,601 ft | May 23 | Sep 27 |
| Eagle Rvr, WI | 1,623 ft | May 25 | Sep 24 |
Frost dates near Boulder Junction
- Star Lake, WI 54561 · last May 25, first Sep 24
- Presque Isle, WI 54557 · last May 25, first Sep 21
- Sayner, WI 54560 · last May 23, first Sep 27
- Manitowish Waters, WI 54545 · last May 25, first Sep 21
- Woodruff, WI 54568 · last May 23, first Sep 27
- Saint Germain, WI 54558 · last May 19, first Oct 3
- Land O Lakes, WI 54540 · last May 25, first Sep 24
- Lac Du Flambeau, WI 54538 · last May 23, first Sep 27
Frequently asked questions
- When is the last frost in Boulder Junction, WI?
- For ZIP code 54512, the average last spring frost (32°F) is May 25, based on NOAA 1991-2020 climate normals for the Rest Lake, WI weather station. There is a 1-in-10 chance of a frost after June 9.
- When is the first frost in Boulder Junction, WI?
- The average first fall frost (32°F) is September 21. 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 54512?
- 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.