Awendaw Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Mcclellanville. 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 17 and the first fall freeze around November 21, a growing season of about 250 days.
- Median at 36°F
- last March 31, first November 9
- Median at 32°F
- last March 17, first November 21
- Median at 28°F
- last March 2, first December 6
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 15 | Apr 10 | Apr 6 | Apr 3 | Mar 31 | Mar 28 | Mar 23 | Mar 19 | Mar 14 |
| 32°F | Apr 4 | Mar 30 | Mar 26 | Mar 21 | Mar 17 | Mar 14 | Mar 8 | Mar 3 | Feb 25 |
| 28°F | Mar 25 | Mar 18 | Mar 12 | Mar 6 | Mar 2 | Feb 26 | Feb 20 | Feb 12 | Jan 31 |
| 24°F | Mar 13 | Mar 3 | Feb 26 | Feb 18 | Feb 10 | Feb 5 | Jan 31 | Jan 25 | Jan 13 |
| 20°F | Feb 28 | Feb 18 | Feb 8 | Feb 2 | Jan 30 | Jan 25 | Jan 18 | Jan 11 | Jan 3 |
| 16°F | Feb 15 | Feb 6 | Jan 31 | Jan 28 | Jan 25 | Jan 19 | Jan 14 | Jan 9 | Jan 5 |
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 28 | Nov 1 | Nov 4 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 20 | Nov 27 |
| 32°F | Nov 4 | Nov 9 | Nov 13 | Nov 17 | Nov 21 | Nov 25 | Nov 30 | Dec 5 | Dec 12 |
| 28°F | Nov 16 | Nov 22 | Nov 28 | Dec 2 | Dec 6 | Dec 12 | Dec 20 | Dec 28 | Jan 5 |
| 24°F | Dec 1 | Dec 9 | Dec 16 | Dec 22 | Dec 30 | Jan 2 | Jan 7 | Jan 14 | Jan 26 |
| 20°F | Dec 18 | Dec 28 | Jan 1 | Jan 5 | Jan 9 | Jan 15 | Jan 20 | Jan 26 | Feb 3 |
| 16°F | Jan 3 | Jan 7 | Jan 11 | Jan 15 | Jan 18 | Jan 24 | Jan 27 | Jan 31 | Feb 8 |
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 | 249 | 240 | 234 | 229 | 225 | 221 | 216 | 209 | 201 |
| 32°F | 282 | 270 | 262 | 256 | 250 | 245 | 240 | 234 | 225 |
| 28°F | 318 | 305 | 296 | 289 | 282 | 275 | 268 | 260 | 249 |
| 24°F | 352 | 339 | 331 | 324 | 316 | 308 | 302 | 293 | 282 |
| 20°F | 365 | 365 | 365 | 353 | 345 | 337 | 331 | 320 | 307 |
| 16°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 350 | 334 |
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
- 96% of years
- 20°F or colder
- 69% of years
- 16°F or colder
- 28% 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
- 2,061
- Cooling degree days, base 65°F
- 2,238
- Growing degree days, base 40°F
- 9,348
- Growing degree days, base 45°F
- 7,624
- Growing degree days, base 50°F
- 6,020
- Growing degree days, base 55°F
- 4,576
- Growing degree days, base 60°F
- 3,320
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 520 | 1 | 82 |
| February | 410 | 1 | 96 |
| March | 280 | 15 | 232 |
| April | 96 | 76 | 431 |
| May | 12 | 238 | 691 |
| June | 0 | 402 | 852 |
| July | 0 | 521 | 986 |
| August | 0 | 482 | 947 |
| September | 1 | 345 | 793 |
| October | 59 | 128 | 535 |
| November | 244 | 25 | 256 |
| December | 440 | 4 | 118 |
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 14 km from Awendaw. 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 USC00385628 (Mcclellanville). Public domain.