Minturn Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Vail. 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 June 21 and the first fall freeze around September 7, a growing season of about 77 days.
- Median at 32°F
- last June 21, first September 7
- Median at 28°F
- last May 31, first September 21
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 | – | – | – | – | – | – | – | – | – |
| 32°F | Jul 9 | Jul 2 | Jun 28 | Jun 24 | Jun 21 | Jun 18 | Jun 15 | Jun 12 | Jun 8 |
| 28°F | Jun 18 | Jun 11 | Jun 7 | Jun 3 | May 31 | May 29 | May 25 | May 21 | May 16 |
| 24°F | May 25 | May 20 | May 17 | May 13 | May 10 | May 7 | May 4 | May 1 | Apr 27 |
| 20°F | May 11 | May 6 | May 3 | Apr 30 | Apr 28 | Apr 24 | Apr 21 | Apr 17 | Apr 13 |
| 16°F | May 1 | Apr 26 | Apr 21 | Apr 18 | Apr 14 | Apr 11 | Apr 7 | Apr 4 | 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 | – | – | – | – | – | – | – | – | – |
| 32°F | Aug 26 | Sep 1 | Sep 3 | Sep 5 | Sep 7 | Sep 10 | Sep 13 | Sep 16 | Sep 20 |
| 28°F | Sep 7 | Sep 12 | Sep 15 | Sep 18 | Sep 21 | Sep 23 | Sep 26 | Sep 29 | Oct 2 |
| 24°F | Sep 20 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 5 | Oct 8 | Oct 11 | Oct 15 |
| 20°F | Oct 1 | Oct 5 | Oct 8 | Oct 12 | Oct 15 | Oct 17 | Oct 19 | Oct 22 | Oct 28 |
| 16°F | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 24 | Oct 27 | Oct 31 | Nov 2 | Nov 7 |
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 | 62 | 55 | 50 | 45 | 40 | 36 | 31 | 28 | 23 |
| 32°F | 95 | 89 | 84 | 80 | 77 | 72 | 67 | 61 | 53 |
| 28°F | 132 | 125 | 119 | 115 | 109 | 105 | 100 | 94 | 86 |
| 24°F | 162 | 157 | 152 | 147 | 143 | 139 | 135 | 130 | 123 |
| 20°F | 188 | 181 | 176 | 172 | 168 | 165 | 160 | 154 | 147 |
| 16°F | 210 | 204 | 200 | 195 | 191 | 187 | 182 | 177 | 168 |
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
- 9,881
- Cooling degree days, base 65°F
- 3
- Growing degree days, base 40°F
- 2,189
- Growing degree days, base 45°F
- 1,388
- Growing degree days, base 50°F
- 744
- Growing degree days, base 55°F
- 288
- Growing degree days, base 60°F
- 56
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,471 | 0 | 0 |
| February | 1,229 | 0 | 0 |
| March | 1,110 | 0 | 0 |
| April | 852 | 0 | 1 |
| May | 598 | 0 | 26 |
| June | 345 | 0 | 130 |
| July | 183 | 2 | 285 |
| August | 237 | 1 | 232 |
| September | 441 | 0 | 68 |
| October | 786 | 0 | 3 |
| November | 1,158 | 0 | 0 |
| December | 1,471 | 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 8.9 km from Minturn. 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 USC00058575 (Vail). Public domain.