Mountain Mesa Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for S Lake Fs. 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 April 5 and the first fall freeze around November 3, a growing season of about 212 days.
- Median at 36°F
- last April 20, first October 21
- Median at 32°F
- last April 5, first November 3
- Median at 28°F
- last March 6, first November 17
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 1 | Apr 29 | Apr 26 | Apr 23 | Apr 20 | Apr 17 | Apr 14 | Apr 11 | Apr 5 |
| 32°F | Apr 21 | Apr 16 | Apr 12 | Apr 9 | Apr 5 | Mar 30 | Mar 22 | Mar 16 | Mar 8 |
| 28°F | Apr 7 | Mar 30 | Mar 18 | Mar 11 | Mar 6 | Mar 1 | Feb 24 | Feb 18 | Feb 8 |
| 24°F | Mar 3 | Feb 23 | Feb 16 | Feb 9 | Feb 4 | Jan 29 | Jan 20 | Jan 12 | Jan 2 |
| 20°F | Feb 6 | Jan 27 | Jan 17 | Jan 11 | Jan 6 | Jan 1 | Dec 29 | Dec 22 | Dec 11 |
| 16°F | Jan 12 | Jan 7 | Jan 3 | Jan 1 | Dec 28 | Dec 26 | Dec 21 | Dec 18 | Dec 14 |
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 | Oct 9 | Oct 13 | Oct 15 | Oct 18 | Oct 21 | Oct 25 | Oct 28 | Nov 1 | Nov 5 |
| 32°F | Oct 18 | Oct 22 | Oct 28 | Oct 31 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 16 |
| 28°F | Oct 31 | Nov 5 | Nov 9 | Nov 13 | Nov 17 | Nov 20 | Nov 23 | Nov 27 | Dec 1 |
| 24°F | Nov 15 | Nov 21 | Nov 25 | Nov 28 | Dec 1 | Dec 5 | Dec 9 | Dec 15 | Dec 24 |
| 20°F | Nov 27 | Dec 2 | Dec 8 | Dec 12 | Dec 19 | Dec 24 | Dec 31 | Jan 5 | Jan 18 |
| 16°F | Dec 10 | Dec 14 | Dec 19 | Dec 22 | Dec 27 | Dec 30 | Jan 2 | Jan 6 | Jan 11 |
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 | 203 | 198 | 193 | 189 | 184 | 181 | 177 | 173 | 168 |
| 32°F | 241 | 233 | 224 | 217 | 212 | 207 | 203 | 197 | 189 |
| 28°F | 286 | 275 | 267 | 260 | 254 | 247 | 240 | 232 | 218 |
| 24°F | 336 | 325 | 318 | 310 | 303 | 295 | 287 | 278 | 264 |
| 20°F | 365 | 365 | 363 | 355 | 347 | 341 | 334 | 327 | 313 |
| 16°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 359 |
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
- 99% of years
- 20°F or colder
- 70% of years
- 16°F or colder
- 16% 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
- 3,079
- Cooling degree days, base 65°F
- 1,723
- Growing degree days, base 40°F
- 7,819
- Growing degree days, base 45°F
- 6,170
- Growing degree days, base 50°F
- 4,736
- Growing degree days, base 55°F
- 3,531
- Growing degree days, base 60°F
- 2,537
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 632 | 0 | 9 |
| February | 487 | 0 | 39 |
| March | 420 | 0 | 102 |
| April | 258 | 5 | 212 |
| May | 55 | 123 | 533 |
| June | 8 | 324 | 766 |
| July | 0 | 514 | 979 |
| August | 0 | 465 | 930 |
| September | 14 | 255 | 691 |
| October | 144 | 37 | 360 |
| November | 409 | 1 | 104 |
| December | 653 | 0 | 10 |
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 4.2 km from Mountain Mesa. 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 USC00048407 (S Lake Fs). Public domain.