Scanlon Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Cloquet. 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 26 and the first fall freeze around September 23, a growing season of about 118 days.
- Median at 36°F
- last June 7, first September 12
- Median at 32°F
- last May 26, first September 23
- Median at 28°F
- last May 12, first October 3
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 21 | Jun 16 | Jun 13 | Jun 10 | Jun 7 | Jun 4 | Jun 2 | May 31 | May 27 |
| 32°F | Jun 9 | Jun 4 | Jun 1 | May 30 | May 26 | May 24 | May 21 | May 18 | May 13 |
| 28°F | May 28 | May 23 | May 19 | May 16 | May 12 | May 9 | May 5 | May 3 | Apr 28 |
| 24°F | May 15 | May 8 | May 5 | May 2 | Apr 30 | Apr 28 | Apr 25 | Apr 22 | Apr 16 |
| 20°F | May 2 | Apr 28 | Apr 25 | Apr 22 | Apr 19 | Apr 16 | Apr 13 | Apr 10 | Apr 5 |
| 16°F | Apr 23 | Apr 18 | Apr 15 | Apr 11 | Apr 8 | Apr 6 | Apr 4 | Apr 1 | Mar 28 |
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 2 | Sep 5 | Sep 9 | Sep 12 | Sep 15 | Sep 18 | Sep 21 | Sep 25 |
| 32°F | Sep 9 | Sep 14 | Sep 18 | Sep 20 | Sep 23 | Sep 26 | Sep 28 | Oct 1 | Oct 4 |
| 28°F | Sep 18 | Sep 24 | Sep 29 | Oct 1 | Oct 3 | Oct 5 | Oct 9 | Oct 13 | Oct 18 |
| 24°F | Oct 1 | Oct 5 | Oct 9 | Oct 12 | Oct 15 | Oct 19 | Oct 23 | Oct 27 | Nov 1 |
| 20°F | Oct 14 | Oct 19 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 3 | Nov 6 | Nov 11 |
| 16°F | Oct 26 | Oct 31 | Nov 2 | Nov 5 | Nov 7 | Nov 10 | Nov 13 | Nov 17 | 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 | 111 | 107 | 102 | 98 | 95 | 90 | 85 | 80 | 72 |
| 32°F | 137 | 132 | 126 | 122 | 118 | 114 | 109 | 104 | 97 |
| 28°F | 163 | 157 | 153 | 147 | 142 | 138 | 134 | 128 | 120 |
| 24°F | 189 | 182 | 176 | 171 | 168 | 164 | 159 | 153 | 144 |
| 20°F | 213 | 206 | 201 | 196 | 192 | 188 | 184 | 179 | 172 |
| 16°F | 229 | 225 | 220 | 216 | 212 | 208 | 204 | 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
- 9,396
- Cooling degree days, base 65°F
- 211
- Growing degree days, base 40°F
- 3,342
- Growing degree days, base 45°F
- 2,448
- Growing degree days, base 50°F
- 1,680
- Growing degree days, base 55°F
- 1,039
- Growing degree days, base 60°F
- 539
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,706 | 0 | 0 |
| February | 1,420 | 0 | 0 |
| March | 1,195 | 0 | 2 |
| April | 776 | 0 | 15 |
| May | 428 | 5 | 122 |
| June | 161 | 31 | 324 |
| July | 53 | 92 | 504 |
| August | 79 | 67 | 453 |
| September | 275 | 17 | 223 |
| October | 682 | 0 | 37 |
| November | 1,097 | 0 | 1 |
| December | 1,524 | 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 7.3 km from Scanlon. 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 USC00211630 (Cloquet). Public domain.