Hubbard County Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Itasca Univ Of Minn. 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 18 and the first fall freeze around September 27, a growing season of about 130 days.
- Median at 36°F
- last May 29, first September 17
- Median at 32°F
- last May 18, first September 27
- Median at 28°F
- last May 6, first October 8
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 10 | Jun 5 | Jun 3 | May 31 | May 29 | May 27 | May 24 | May 21 | May 17 |
| 32°F | May 31 | May 28 | May 24 | May 21 | May 18 | May 15 | May 11 | May 8 | May 3 |
| 28°F | May 20 | May 16 | May 12 | May 9 | May 6 | May 3 | Apr 30 | Apr 28 | Apr 24 |
| 24°F | May 10 | May 4 | May 2 | Apr 30 | Apr 28 | Apr 25 | Apr 22 | Apr 19 | Apr 14 |
| 20°F | Apr 30 | Apr 26 | Apr 22 | Apr 20 | Apr 18 | Apr 16 | Apr 13 | Apr 9 | Apr 5 |
| 16°F | Apr 23 | Apr 19 | Apr 16 | Apr 13 | Apr 10 | Apr 7 | Apr 5 | Apr 2 | 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 | Sep 1 | Sep 6 | Sep 10 | Sep 14 | Sep 17 | Sep 19 | Sep 22 | Sep 25 | Sep 28 |
| 32°F | Sep 12 | Sep 18 | Sep 21 | Sep 24 | Sep 27 | Sep 30 | Oct 1 | Oct 5 | Oct 10 |
| 28°F | Sep 23 | Sep 29 | Oct 1 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 18 | Oct 22 |
| 24°F | Oct 5 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 30 | Nov 3 |
| 20°F | Oct 17 | Oct 22 | Oct 26 | Oct 29 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 12 |
| 16°F | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 7 | Nov 10 | Nov 13 | Nov 16 | Nov 21 |
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 | 127 | 121 | 117 | 114 | 111 | 107 | 102 | 97 | 90 |
| 32°F | 149 | 143 | 138 | 134 | 130 | 126 | 122 | 117 | 111 |
| 28°F | 172 | 166 | 162 | 157 | 153 | 149 | 144 | 139 | 132 |
| 24°F | 194 | 187 | 183 | 178 | 174 | 170 | 166 | 161 | 153 |
| 20°F | 212 | 207 | 202 | 198 | 195 | 191 | 187 | 182 | 175 |
| 16°F | 226 | 220 | 216 | 212 | 209 | 206 | 203 | 198 | 192 |
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
- 9,794
- Cooling degree days, base 65°F
- 262
- Growing degree days, base 40°F
- 3,446
- Growing degree days, base 45°F
- 2,564
- Growing degree days, base 50°F
- 1,796
- Growing degree days, base 55°F
- 1,145
- Growing degree days, base 60°F
- 626
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,820 | 0 | 0 |
| February | 1,523 | 0 | 0 |
| March | 1,271 | 0 | 2 |
| April | 795 | 0 | 18 |
| May | 407 | 10 | 151 |
| June | 127 | 50 | 377 |
| July | 47 | 105 | 522 |
| August | 75 | 77 | 467 |
| September | 284 | 20 | 220 |
| October | 705 | 1 | 38 |
| November | 1,149 | 0 | 1 |
| December | 1,592 | 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 24.5 km from Hubbard County. 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 USC00214106 (Itasca Univ Of Minn). Public domain.