Shelter Cove Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Shelter Cove Aviation. A median date has an even chance of a later freeze in spring, or an earlier one in fall.
A freeze (32°F or colder) happens in only 9 percent of years at Shelter Cove Aviation, so there is no typical freeze season.
- Median at 36°F
- last February 15, first January 12
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 | Apr 7 | Mar 28 | Mar 9 | Feb 28 | Feb 15 | Jan 29 | Jan 16 | Jan 3 | Dec 18 |
| 32°F | – | – | – | – | – | – | – | – | – |
| 28°F | – | – | – | – | – | – | – | – | – |
| 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 | Dec 4 | Dec 13 | Dec 26 | Jan 2 | Jan 12 | Jan 24 | Feb 10 | Mar 1 | Mar 23 |
| 32°F | – | – | – | – | – | – | – | – | – |
| 28°F | – | – | – | – | – | – | – | – | – |
| 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 | 365 | 365 | 365 | 365 | 360 | 343 | 326 | 301 | 277 |
| 32°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
| 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
- 54% of years
- 32°F or colder
- 9% of years
- 28°F or colder
- 1% of years
- 24°F or colder
- 0% 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
- 3,074
- Cooling degree days, base 65°F
- 117
- Growing degree days, base 40°F
- 6,169
- Growing degree days, base 45°F
- 4,356
- Growing degree days, base 50°F
- 2,616
- Growing degree days, base 55°F
- 1,211
- Growing degree days, base 60°F
- 428
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 391 | 0 | 100 |
| February | 336 | 1 | 102 |
| March | 350 | 1 | 134 |
| April | 320 | 1 | 138 |
| May | 253 | 4 | 216 |
| June | 165 | 14 | 299 |
| July | 157 | 12 | 321 |
| August | 144 | 17 | 338 |
| September | 129 | 39 | 360 |
| October | 167 | 25 | 325 |
| November | 285 | 3 | 174 |
| December | 378 | 1 | 111 |
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 0.3 km from Shelter Cove. 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 USC00048163 (Shelter Cove Aviation). Public domain.