Moreland Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Blackfoot Fire Dept. 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 3, a growing season of about 149 days.
- Median at 36°F
- last May 23, first September 21
- Median at 32°F
- last May 5, first October 3
- Median at 28°F
- last April 22, first October 16
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 14 | Jun 6 | Jun 2 | May 27 | May 23 | May 19 | May 16 | May 12 | May 8 |
| 32°F | May 22 | May 15 | May 11 | May 8 | May 5 | May 3 | Apr 30 | Apr 28 | Apr 23 |
| 28°F | May 4 | Apr 30 | Apr 28 | Apr 25 | Apr 22 | Apr 19 | Apr 15 | Apr 12 | Apr 6 |
| 24°F | Apr 21 | Apr 16 | Apr 12 | Apr 8 | Apr 5 | Apr 2 | Mar 30 | Mar 23 | Mar 15 |
| 20°F | Apr 6 | Apr 1 | Mar 27 | Mar 22 | Mar 16 | Mar 12 | Mar 9 | Mar 5 | Feb 28 |
| 16°F | Mar 23 | Mar 14 | Mar 10 | Mar 6 | Mar 4 | Mar 1 | Feb 27 | Feb 22 | Feb 16 |
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 4 | Sep 10 | Sep 14 | Sep 18 | Sep 21 | Sep 24 | Sep 28 | Oct 1 | Oct 5 |
| 32°F | Sep 16 | Sep 23 | Sep 28 | Oct 1 | Oct 3 | Oct 6 | Oct 9 | Oct 13 | Oct 18 |
| 28°F | Sep 30 | Oct 5 | Oct 9 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 24 | Oct 31 |
| 24°F | Oct 13 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 5 | Nov 11 |
| 20°F | Oct 22 | Oct 27 | Oct 31 | Nov 2 | Nov 6 | Nov 10 | Nov 13 | Nov 18 | Nov 23 |
| 16°F | Oct 30 | Nov 4 | Nov 10 | Nov 13 | Nov 17 | Nov 20 | Nov 24 | Nov 27 | Dec 1 |
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 | 142 | 134 | 129 | 123 | 118 | 113 | 109 | 100 | 90 |
| 32°F | 169 | 162 | 157 | 153 | 149 | 145 | 139 | 133 | 125 |
| 28°F | 196 | 189 | 184 | 179 | 176 | 172 | 168 | 163 | 155 |
| 24°F | 228 | 218 | 213 | 207 | 203 | 198 | 194 | 188 | 181 |
| 20°F | 258 | 248 | 243 | 239 | 233 | 228 | 221 | 215 | 204 |
| 16°F | 279 | 271 | 266 | 261 | 256 | 250 | 245 | 239 | 231 |
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
- 6,990
- Cooling degree days, base 65°F
- 519
- Growing degree days, base 40°F
- 4,305
- Growing degree days, base 45°F
- 3,240
- Growing degree days, base 50°F
- 2,337
- Growing degree days, base 55°F
- 1,586
- Growing degree days, base 60°F
- 978
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,271 | 0 | 0 |
| February | 1,015 | 0 | 0 |
| March | 808 | 0 | 7 |
| April | 569 | 0 | 43 |
| May | 315 | 12 | 195 |
| June | 120 | 68 | 401 |
| July | 18 | 218 | 665 |
| August | 23 | 179 | 622 |
| September | 174 | 41 | 329 |
| October | 536 | 1 | 71 |
| November | 896 | 0 | 4 |
| December | 1,246 | 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 8.6 km from Moreland. 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 USC00100915 (Blackfoot Fire Dept). Public domain.