Minatare Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Scottsbluff Heilig 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 4, a growing season of about 149 days.
- Median at 36°F
- last May 16, first September 25
- Median at 32°F
- last May 5, first October 4
- Median at 28°F
- last April 28, first October 13
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 | May 31 | May 25 | May 22 | May 19 | May 16 | May 14 | May 11 | May 8 | May 5 |
| 32°F | May 18 | May 13 | May 11 | May 8 | May 5 | May 3 | May 1 | Apr 29 | Apr 25 |
| 28°F | May 9 | May 5 | May 2 | Apr 30 | Apr 28 | Apr 26 | Apr 22 | Apr 18 | Apr 14 |
| 24°F | Apr 30 | Apr 26 | Apr 23 | Apr 19 | Apr 17 | Apr 13 | Apr 10 | Apr 6 | Apr 2 |
| 20°F | Apr 23 | Apr 18 | Apr 13 | Apr 9 | Apr 5 | Apr 1 | Mar 29 | Mar 24 | Mar 17 |
| 16°F | Apr 14 | Apr 9 | Apr 3 | Mar 31 | Mar 25 | Mar 20 | Mar 15 | Mar 9 | Mar 5 |
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 12 | Sep 16 | Sep 19 | Sep 23 | Sep 25 | Sep 27 | Sep 30 | Oct 2 | Oct 6 |
| 32°F | Sep 21 | Sep 25 | Sep 28 | Oct 1 | Oct 4 | Oct 6 | Oct 8 | Oct 11 | Oct 15 |
| 28°F | Sep 30 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 15 | Oct 17 | Oct 20 | Oct 24 |
| 24°F | Oct 8 | Oct 13 | Oct 16 | Oct 19 | Oct 21 | Oct 24 | Oct 26 | Oct 28 | Nov 1 |
| 20°F | Oct 16 | Oct 20 | Oct 23 | Oct 26 | Oct 28 | Nov 1 | Nov 3 | Nov 6 | Nov 12 |
| 16°F | Oct 20 | Oct 25 | Oct 30 | Nov 2 | Nov 5 | Nov 8 | Nov 12 | Nov 16 | Nov 22 |
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 | 147 | 142 | 138 | 134 | 130 | 127 | 123 | 119 | 113 |
| 32°F | 166 | 160 | 156 | 152 | 149 | 146 | 142 | 138 | 131 |
| 28°F | 185 | 179 | 174 | 170 | 167 | 164 | 160 | 157 | 151 |
| 24°F | 205 | 199 | 194 | 190 | 186 | 183 | 179 | 174 | 168 |
| 20°F | 230 | 220 | 214 | 209 | 205 | 200 | 196 | 192 | 185 |
| 16°F | 250 | 241 | 235 | 229 | 224 | 219 | 213 | 207 | 199 |
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
- 6,312
- Cooling degree days, base 65°F
- 853
- Growing degree days, base 40°F
- 5,077
- Growing degree days, base 45°F
- 3,933
- Growing degree days, base 50°F
- 2,950
- Growing degree days, base 55°F
- 2,120
- Growing degree days, base 60°F
- 1,425
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,138 | 0 | 1 |
| February | 957 | 0 | 2 |
| March | 777 | 0 | 19 |
| April | 528 | 1 | 71 |
| May | 255 | 29 | 269 |
| June | 45 | 157 | 563 |
| July | 4 | 322 | 782 |
| August | 12 | 262 | 714 |
| September | 126 | 81 | 414 |
| October | 490 | 2 | 105 |
| November | 834 | 0 | 10 |
| December | 1,147 | 0 | 1 |
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 10.1 km from Minatare. 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 USW00024028 (Scottsbluff Heilig AP). Public domain.