Komatke Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Laveen 3 Sse. 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 January 14 and the first fall freeze around December 22, a growing season of about 343 days.
- Median at 36°F
- last February 6, first December 8
- Median at 32°F
- last January 14, first December 22
- Median at 28°F
- last January 5, first January 2
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 | Mar 1 | Feb 23 | Feb 17 | Feb 11 | Feb 6 | Feb 2 | Jan 28 | Jan 20 | Jan 8 |
| 32°F | Feb 12 | Feb 4 | Jan 29 | Jan 21 | Jan 14 | Jan 8 | Jan 3 | Dec 29 | Dec 19 |
| 28°F | Feb 3 | Jan 23 | Jan 15 | Jan 8 | Jan 5 | Jan 3 | Dec 31 | Dec 24 | Dec 13 |
| 24°F | – | – | – | – | – | – | – | – | – |
| 20°F | – | – | – | – | – | – | – | – | – |
| 16°F | – | – | – | – | – | – | – | – | – |
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 | Nov 22 | Nov 27 | Dec 1 | Dec 4 | Dec 8 | Dec 11 | Dec 15 | Dec 19 | Dec 24 |
| 32°F | Dec 1 | Dec 7 | Dec 12 | Dec 17 | Dec 22 | Dec 27 | Dec 31 | Jan 7 | Jan 22 |
| 28°F | Dec 11 | Dec 20 | Dec 28 | Dec 31 | Jan 2 | Jan 6 | Jan 9 | Jan 18 | Jan 30 |
| 24°F | – | – | – | – | – | – | – | – | – |
| 20°F | – | – | – | – | – | – | – | – | – |
| 16°F | – | – | – | – | – | – | – | – | – |
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 | 335 | 323 | 315 | 309 | 302 | 296 | 289 | 283 | 274 |
| 32°F | 365 | 363 | 355 | 348 | 343 | 335 | 330 | 321 | 310 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 362 | 349 |
| 24°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
| 20°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
| 16°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
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
- 85% of years
- 28°F or colder
- 25% of years
- 24°F or colder
- 2% of years
- 20°F or colder
- 0% of years
- 16°F or colder
- 0% 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
- 1,103
- Cooling degree days, base 65°F
- 4,398
- Growing degree days, base 40°F
- 12,420
- Growing degree days, base 45°F
- 10,602
- Growing degree days, base 50°F
- 8,822
- Growing degree days, base 55°F
- 7,156
- Growing degree days, base 60°F
- 5,675
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 316 | 1 | 169 |
| February | 199 | 8 | 233 |
| March | 89 | 73 | 450 |
| April | 20 | 218 | 648 |
| May | 1 | 491 | 955 |
| June | 0 | 757 | 1,207 |
| July | 0 | 911 | 1,376 |
| August | 0 | 879 | 1,344 |
| September | 0 | 673 | 1,124 |
| October | 10 | 325 | 780 |
| November | 121 | 61 | 393 |
| December | 348 | 1 | 144 |
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 3.4 km from Komatke. 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 USC00024829 (Laveen 3 Sse). Public domain.