Crofton Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Hopkinsville. 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 2, a growing season of about 211 days.
- Median at 36°F
- last April 14, first October 24
- Median at 32°F
- last April 4, first November 2
- Median at 28°F
- last March 22, first November 13
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 1 | Apr 25 | Apr 21 | Apr 18 | Apr 14 | Apr 11 | Apr 8 | Apr 5 | Mar 31 |
| 32°F | Apr 19 | Apr 13 | Apr 9 | Apr 6 | Apr 4 | Apr 1 | Mar 29 | Mar 24 | Mar 18 |
| 28°F | Apr 7 | Apr 2 | Mar 30 | Mar 26 | Mar 22 | Mar 18 | Mar 14 | Mar 9 | Mar 2 |
| 24°F | Mar 29 | Mar 22 | Mar 18 | Mar 13 | Mar 9 | Mar 5 | Mar 1 | Feb 24 | Feb 16 |
| 20°F | Mar 18 | Mar 12 | Mar 5 | Mar 1 | Feb 26 | Feb 21 | Feb 15 | Feb 8 | Feb 1 |
| 16°F | Mar 9 | Mar 1 | Feb 25 | Feb 18 | Feb 12 | Feb 7 | Feb 2 | Jan 28 | Jan 17 |
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 11 | Oct 16 | Oct 19 | Oct 22 | Oct 24 | Oct 26 | Oct 28 | Nov 1 | Nov 5 |
| 32°F | Oct 20 | Oct 24 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 12 | Nov 18 |
| 28°F | Oct 31 | Nov 3 | Nov 7 | Nov 10 | Nov 13 | Nov 17 | Nov 22 | Nov 26 | Dec 1 |
| 24°F | Nov 8 | Nov 14 | Nov 18 | Nov 22 | Nov 25 | Nov 29 | Dec 2 | Dec 7 | Dec 16 |
| 20°F | Nov 18 | Nov 25 | Nov 30 | Dec 4 | Dec 8 | Dec 12 | Dec 19 | Dec 25 | Jan 1 |
| 16°F | Nov 30 | Dec 6 | Dec 13 | Dec 21 | Dec 26 | Dec 31 | Jan 4 | Jan 10 | Jan 20 |
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 | 210 | 204 | 199 | 195 | 191 | 187 | 183 | 178 | 172 |
| 32°F | 236 | 227 | 220 | 216 | 211 | 207 | 203 | 198 | 191 |
| 28°F | 262 | 252 | 245 | 240 | 235 | 230 | 225 | 220 | 213 |
| 24°F | 290 | 280 | 273 | 267 | 262 | 255 | 249 | 244 | 236 |
| 20°F | 315 | 304 | 299 | 292 | 286 | 280 | 273 | 266 | 256 |
| 16°F | 342 | 330 | 323 | 317 | 310 | 303 | 297 | 290 | 280 |
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
- 98% 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
- 4,026
- Cooling degree days, base 65°F
- 1,610
- Growing degree days, base 40°F
- 7,280
- Growing degree days, base 45°F
- 5,855
- Growing degree days, base 50°F
- 4,577
- Growing degree days, base 55°F
- 3,440
- Growing degree days, base 60°F
- 2,453
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 914 | 0 | 15 |
| February | 714 | 1 | 33 |
| March | 532 | 4 | 95 |
| April | 243 | 36 | 279 |
| May | 67 | 143 | 542 |
| June | 4 | 319 | 765 |
| July | 0 | 437 | 902 |
| August | 1 | 399 | 863 |
| September | 27 | 218 | 640 |
| October | 213 | 50 | 324 |
| November | 511 | 4 | 96 |
| December | 800 | 0 | 23 |
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 22.3 km from Crofton. 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 USC00153994 (Hopkinsville). Public domain.