Eolia Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Clarksville L&d 24. 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 4 and the first fall freeze around November 1, a growing season of about 208 days.
- Median at 36°F
- last April 16, first October 23
- Median at 32°F
- last April 4, first November 1
- Median at 28°F
- last March 24, first November 11
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 3 | Apr 27 | Apr 24 | Apr 20 | Apr 16 | Apr 12 | Apr 9 | Apr 6 | Apr 2 |
| 32°F | Apr 23 | Apr 15 | Apr 10 | Apr 7 | Apr 4 | Apr 1 | Mar 30 | Mar 26 | Mar 20 |
| 28°F | Apr 8 | Apr 3 | Mar 31 | Mar 28 | Mar 24 | Mar 22 | Mar 18 | Mar 15 | Mar 9 |
| 24°F | Mar 31 | Mar 27 | Mar 22 | Mar 18 | Mar 15 | Mar 12 | Mar 9 | Mar 5 | Feb 28 |
| 20°F | Mar 23 | Mar 17 | Mar 13 | Mar 10 | Mar 7 | Mar 4 | Mar 2 | Feb 27 | Feb 20 |
| 16°F | Mar 15 | Mar 11 | Mar 6 | Mar 3 | Feb 28 | Feb 26 | Feb 21 | Feb 16 | Feb 8 |
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 15 | Oct 18 | Oct 20 | Oct 23 | Oct 25 | Oct 27 | Oct 30 | Nov 2 |
| 32°F | Oct 19 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 2 | Nov 5 | Nov 9 | Nov 15 |
| 28°F | Oct 30 | Nov 1 | Nov 4 | Nov 7 | Nov 11 | Nov 13 | Nov 16 | Nov 21 | Nov 26 |
| 24°F | Nov 5 | Nov 10 | Nov 13 | Nov 16 | Nov 20 | Nov 23 | Nov 27 | Dec 1 | Dec 6 |
| 20°F | Nov 12 | Nov 17 | Nov 21 | Nov 26 | Nov 29 | Dec 2 | Dec 5 | Dec 10 | Dec 15 |
| 16°F | Nov 20 | Nov 27 | Dec 1 | Dec 5 | Dec 8 | Dec 12 | Dec 17 | Dec 22 | Dec 27 |
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 | 207 | 201 | 197 | 192 | 188 | 183 | 179 | 174 | 167 |
| 32°F | 230 | 223 | 217 | 212 | 208 | 205 | 201 | 196 | 189 |
| 28°F | 250 | 243 | 239 | 234 | 229 | 225 | 220 | 216 | 210 |
| 24°F | 270 | 263 | 257 | 253 | 249 | 244 | 240 | 235 | 227 |
| 20°F | 289 | 281 | 276 | 271 | 266 | 261 | 256 | 251 | 245 |
| 16°F | 309 | 300 | 294 | 288 | 284 | 279 | 273 | 267 | 259 |
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
- 100% of years
- 20°F or colder
- 100% of years
- 16°F or colder
- 100% 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
- 5,166
- Cooling degree days, base 65°F
- 1,324
- Growing degree days, base 40°F
- 6,360
- Growing degree days, base 45°F
- 5,091
- Growing degree days, base 50°F
- 3,955
- Growing degree days, base 55°F
- 2,950
- Growing degree days, base 60°F
- 2,070
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,144 | 0 | 2 |
| February | 911 | 0 | 6 |
| March | 695 | 2 | 51 |
| April | 335 | 17 | 192 |
| May | 113 | 95 | 449 |
| June | 10 | 275 | 715 |
| July | 1 | 399 | 863 |
| August | 2 | 350 | 814 |
| September | 47 | 159 | 563 |
| October | 284 | 27 | 245 |
| November | 637 | 1 | 50 |
| December | 989 | 0 | 5 |
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 17.6 km from Eolia. 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 USC00231640 (Clarksville L&d 24). Public domain.