Willow Creek Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Orleans. 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 March 12 and the first fall freeze around November 26, a growing season of about 262 days.
- Median at 36°F
- last April 12, first November 5
- Median at 32°F
- last March 12, first November 26
- Median at 28°F
- last January 28, first December 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 2 | Apr 25 | Apr 20 | Apr 16 | Apr 12 | Apr 8 | Apr 4 | Mar 31 | Mar 22 |
| 32°F | Apr 9 | Mar 31 | Mar 26 | Mar 19 | Mar 12 | Mar 3 | Feb 25 | Feb 14 | Jan 26 |
| 28°F | Mar 3 | Feb 24 | Feb 16 | Feb 8 | Jan 28 | Jan 15 | Jan 6 | Dec 30 | Dec 13 |
| 24°F | Jan 29 | Jan 20 | Jan 12 | Jan 5 | Dec 31 | Dec 27 | Dec 17 | Dec 9 | Nov 29 |
| 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 | Oct 17 | Oct 24 | Oct 29 | Nov 1 | Nov 5 | Nov 9 | Nov 14 | Nov 20 | Nov 27 |
| 32°F | Oct 31 | Nov 7 | Nov 13 | Nov 20 | Nov 26 | Dec 1 | Dec 6 | Dec 13 | Dec 21 |
| 28°F | Nov 16 | Nov 28 | Dec 4 | Dec 10 | Dec 17 | Dec 24 | Jan 1 | Jan 10 | Jan 31 |
| 24°F | Nov 21 | Dec 1 | Dec 8 | Dec 14 | Dec 22 | Dec 29 | Jan 2 | Jan 10 | Jan 21 |
| 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 | 240 | 229 | 222 | 216 | 208 | 203 | 197 | 190 | 180 |
| 32°F | 313 | 293 | 282 | 272 | 262 | 254 | 244 | 234 | 220 |
| 28°F | 365 | 356 | 345 | 334 | 326 | 316 | 308 | 297 | 282 |
| 24°F | 365 | 365 | 365 | 365 | 365 | 365 | 358 | 347 | 334 |
| 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
- 100% of years
- 28°F or colder
- 86% of years
- 24°F or colder
- 35% of years
- 20°F or colder
- 7% 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
- 3,457
- Cooling degree days, base 65°F
- 860
- Growing degree days, base 40°F
- 6,583
- Growing degree days, base 45°F
- 4,959
- Growing degree days, base 50°F
- 3,580
- Growing degree days, base 55°F
- 2,460
- Growing degree days, base 60°F
- 1,559
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 668 | 0 | 4 |
| February | 504 | 0 | 22 |
| March | 422 | 0 | 91 |
| April | 280 | 4 | 190 |
| May | 127 | 43 | 382 |
| June | 39 | 117 | 528 |
| July | 2 | 293 | 756 |
| August | 2 | 261 | 724 |
| September | 21 | 131 | 559 |
| October | 209 | 12 | 272 |
| November | 488 | 0 | 47 |
| December | 697 | 0 | 6 |
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 41.9 km from Willow Creek. 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 USC00046508 (Orleans). Public domain.