Woodruff Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Minocqua. A median date has an even chance of a later freeze in spring, or an earlier one in fall.
The last spring freeze typically comes around May 23 and the first fall freeze around September 27, a growing season of about 127 days.
- Median at 36°F
- last June 1, first September 15
- Median at 32°F
- last May 23, first September 27
- Median at 28°F
- last May 10, first October 6
Last freeze in spring
The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 17 | Jun 11 | Jun 7 | Jun 4 | Jun 1 | May 31 | May 28 | May 24 | May 20 |
| 32°F | Jun 6 | Jun 1 | May 29 | May 26 | May 23 | May 20 | May 17 | May 13 | May 7 |
| 28°F | May 25 | May 20 | May 16 | May 12 | May 10 | May 7 | May 4 | Apr 30 | Apr 27 |
| 24°F | May 13 | May 8 | May 4 | May 1 | Apr 30 | Apr 27 | Apr 25 | Apr 22 | Apr 17 |
| 20°F | Apr 30 | Apr 27 | Apr 24 | Apr 22 | Apr 19 | Apr 16 | Apr 14 | Apr 11 | Apr 6 |
| 16°F | Apr 24 | Apr 20 | Apr 17 | Apr 14 | Apr 11 | Apr 9 | Apr 6 | Apr 3 | Mar 31 |
First freeze in fall
The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 29 | Sep 3 | Sep 7 | Sep 12 | Sep 15 | Sep 19 | Sep 22 | Sep 26 | Sep 30 |
| 32°F | Sep 9 | Sep 16 | Sep 20 | Sep 24 | Sep 27 | Sep 30 | Oct 2 | Oct 6 | Oct 10 |
| 28°F | Sep 21 | Sep 27 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 14 | Oct 18 | Oct 24 |
| 24°F | Oct 4 | Oct 9 | Oct 14 | Oct 18 | Oct 22 | Oct 25 | Oct 29 | Nov 1 | Nov 6 |
| 20°F | Oct 19 | Oct 25 | Oct 29 | Nov 1 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 16 |
| 16°F | Oct 29 | Nov 2 | Nov 6 | Nov 8 | Nov 11 | Nov 13 | Nov 16 | Nov 19 | Nov 24 |
Growing season length
Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | 124 | 117 | 111 | 107 | 103 | 99 | 94 | 88 | 81 |
| 32°F | 147 | 140 | 135 | 131 | 127 | 122 | 118 | 112 | 105 |
| 28°F | 171 | 164 | 158 | 153 | 149 | 145 | 141 | 136 | 128 |
| 24°F | 193 | 186 | 181 | 177 | 172 | 168 | 164 | 159 | 151 |
| 20°F | 215 | 208 | 203 | 199 | 194 | 190 | 186 | 181 | 175 |
| 16°F | 230 | 224 | 220 | 216 | 212 | 208 | 204 | 199 | 193 |
How often it gets that cold
The share of years with at least one night at or below each temperature.
- 36°F or colder
- 100% of years
- 32°F or colder
- 100% of years
- 28°F or colder
- 100% of years
- 24°F or colder
- 100% of years
- 20°F or colder
- 100% of years
- 16°F or colder
- 100% of years
Degree days
A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.
- Heating degree days, base 65°F
- 9,476
- Cooling degree days, base 65°F
- 208
- Growing degree days, base 40°F
- 3,298
- Growing degree days, base 45°F
- 2,426
- Growing degree days, base 50°F
- 1,670
- Growing degree days, base 55°F
- 1,031
- Growing degree days, base 60°F
- 535
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,691 | 0 | 0 |
| February | 1,429 | 0 | 0 |
| March | 1,249 | 0 | 3 |
| April | 827 | 0 | 16 |
| May | 427 | 11 | 146 |
| June | 139 | 47 | 364 |
| July | 68 | 85 | 482 |
| August | 105 | 48 | 409 |
| September | 297 | 16 | 210 |
| October | 686 | 1 | 39 |
| November | 1,073 | 0 | 2 |
| December | 1,486 | 0 | 0 |
What this means
NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.
The station is 2.8 km from Woodruff. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.
More
Sources
NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00475516 (Minocqua). Public domain.