Spring Glen Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Price Carbon CO 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 3 and the first fall freeze around October 12, a growing season of about 160 days.
- Median at 36°F
- last May 18, first October 2
- Median at 32°F
- last May 3, first October 12
- Median at 28°F
- last April 22, first October 22
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 5 | May 29 | May 24 | May 21 | May 18 | May 15 | May 10 | May 6 | May 3 |
| 32°F | May 21 | May 15 | May 10 | May 6 | May 3 | May 1 | Apr 28 | Apr 25 | Apr 20 |
| 28°F | May 8 | May 3 | Apr 29 | Apr 25 | Apr 22 | Apr 19 | Apr 16 | Apr 13 | Apr 8 |
| 24°F | Apr 26 | Apr 20 | Apr 16 | Apr 13 | Apr 9 | Apr 6 | Apr 3 | Mar 28 | Mar 18 |
| 20°F | Apr 13 | Apr 5 | Mar 31 | Mar 26 | Mar 19 | Mar 14 | Mar 10 | Mar 7 | Mar 2 |
| 16°F | Mar 25 | Mar 12 | Mar 8 | Mar 5 | Mar 1 | Feb 27 | Feb 22 | Feb 18 | Feb 12 |
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 21 | Sep 25 | Sep 27 | Sep 30 | Oct 2 | Oct 4 | Oct 7 | Oct 11 | Oct 16 |
| 32°F | Sep 29 | Oct 3 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 17 | Oct 20 | Oct 25 |
| 28°F | Oct 8 | Oct 12 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 29 | Nov 1 | Nov 5 |
| 24°F | Oct 19 | Oct 23 | Oct 26 | Oct 29 | Nov 1 | Nov 4 | Nov 7 | Nov 11 | Nov 15 |
| 20°F | Oct 26 | Nov 2 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 18 | Nov 20 | Nov 24 |
| 16°F | Nov 7 | Nov 12 | Nov 16 | Nov 18 | Nov 20 | Nov 23 | Nov 26 | Nov 30 | Dec 6 |
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 | 156 | 151 | 145 | 141 | 136 | 131 | 126 | 122 | 114 |
| 32°F | 178 | 172 | 168 | 165 | 160 | 156 | 152 | 146 | 138 |
| 28°F | 200 | 192 | 188 | 185 | 180 | 177 | 172 | 167 | 161 |
| 24°F | 228 | 220 | 214 | 209 | 204 | 200 | 195 | 189 | 182 |
| 20°F | 256 | 248 | 242 | 237 | 232 | 227 | 220 | 214 | 205 |
| 16°F | 285 | 278 | 272 | 266 | 261 | 256 | 250 | 244 | 234 |
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
- 6,379
- Cooling degree days, base 65°F
- 744
- Growing degree days, base 40°F
- 4,887
- Growing degree days, base 45°F
- 3,774
- Growing degree days, base 50°F
- 2,814
- Growing degree days, base 55°F
- 2,001
- Growing degree days, base 60°F
- 1,313
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,224 | 0 | 0 |
| February | 939 | 0 | 0 |
| March | 747 | 0 | 11 |
| April | 524 | 0 | 54 |
| May | 254 | 20 | 257 |
| June | 54 | 133 | 530 |
| July | 1 | 308 | 772 |
| August | 6 | 227 | 687 |
| September | 106 | 54 | 403 |
| October | 461 | 1 | 98 |
| November | 857 | 0 | 2 |
| December | 1,206 | 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 10.1 km from Spring Glen. 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 USW00093141 (Price Carbon CO AP). Public domain.