Howards Grove Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Sheboygan CO Mem AP. 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 5 and the first fall freeze around October 8, a growing season of about 154 days.
- Median at 36°F
- last May 19, first September 29
- Median at 32°F
- last May 5, first October 8
- Median at 28°F
- last April 23, first October 21
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 2 | May 29 | May 26 | May 22 | May 19 | May 17 | May 13 | May 9 | May 3 |
| 32°F | May 21 | May 17 | May 13 | May 9 | May 5 | May 2 | Apr 30 | Apr 27 | Apr 22 |
| 28°F | May 9 | May 2 | Apr 28 | Apr 26 | Apr 23 | Apr 20 | Apr 16 | Apr 13 | Apr 8 |
| 24°F | Apr 23 | Apr 19 | Apr 15 | Apr 11 | Apr 8 | Apr 6 | Apr 3 | Apr 1 | Mar 27 |
| 20°F | Apr 11 | Apr 6 | Apr 3 | Apr 1 | Mar 29 | Mar 27 | Mar 23 | Mar 20 | Mar 15 |
| 16°F | Apr 2 | Mar 30 | Mar 26 | Mar 23 | Mar 21 | Mar 18 | Mar 15 | Mar 11 | Mar 8 |
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 | Sep 17 | Sep 21 | Sep 24 | Sep 27 | Sep 29 | Oct 1 | Oct 3 | Oct 6 | Oct 11 |
| 32°F | Sep 26 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 18 | Oct 23 |
| 28°F | Oct 5 | Oct 10 | Oct 14 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Oct 31 | Nov 3 |
| 24°F | Oct 17 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 16 |
| 20°F | Oct 31 | Nov 3 | Nov 7 | Nov 10 | Nov 14 | Nov 17 | Nov 20 | Nov 23 | Nov 28 |
| 16°F | Nov 9 | Nov 14 | Nov 17 | Nov 20 | Nov 23 | Nov 25 | Nov 28 | Dec 1 | Dec 7 |
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 | 151 | 144 | 138 | 134 | 131 | 127 | 123 | 119 | 113 |
| 32°F | 173 | 167 | 162 | 158 | 154 | 149 | 144 | 139 | 132 |
| 28°F | 201 | 193 | 188 | 184 | 180 | 176 | 171 | 166 | 158 |
| 24°F | 227 | 219 | 214 | 209 | 206 | 201 | 196 | 191 | 184 |
| 20°F | 249 | 243 | 237 | 233 | 229 | 224 | 220 | 215 | 209 |
| 16°F | 268 | 261 | 256 | 251 | 248 | 244 | 239 | 234 | 227 |
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
- 7,571
- Cooling degree days, base 65°F
- 407
- Growing degree days, base 40°F
- 4,097
- Growing degree days, base 45°F
- 3,086
- Growing degree days, base 50°F
- 2,210
- Growing degree days, base 55°F
- 1,463
- Growing degree days, base 60°F
- 852
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,415 | 0 | 0 |
| February | 1,201 | 0 | 0 |
| March | 1,019 | 0 | 7 |
| April | 659 | 0 | 29 |
| May | 348 | 13 | 177 |
| June | 93 | 78 | 436 |
| July | 26 | 157 | 597 |
| August | 34 | 118 | 549 |
| September | 175 | 37 | 320 |
| October | 514 | 3 | 86 |
| November | 861 | 0 | 9 |
| December | 1,226 | 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 7.6 km from Howards Grove. 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 USW00004841 (Sheboygan CO Mem AP). Public domain.