Spring Hill Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Thompson Stn. 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 3 and the first fall freeze around November 1, a growing season of about 211 days.
- Median at 36°F
- last April 17, first October 23
- Median at 32°F
- last April 3, first November 1
- Median at 28°F
- last March 23, 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 2 | Apr 28 | Apr 24 | Apr 20 | Apr 17 | Apr 14 | Apr 10 | Apr 6 | Apr 1 |
| 32°F | Apr 22 | Apr 15 | Apr 10 | Apr 6 | Apr 3 | Mar 31 | Mar 28 | Mar 22 | Mar 17 |
| 28°F | Apr 11 | Apr 3 | Mar 31 | Mar 26 | Mar 23 | Mar 18 | Mar 14 | Mar 8 | Mar 2 |
| 24°F | Apr 1 | Mar 23 | Mar 17 | Mar 13 | Mar 8 | Mar 4 | Feb 28 | Feb 25 | Feb 17 |
| 20°F | Mar 16 | Mar 10 | Mar 4 | Mar 1 | Feb 25 | Feb 21 | Feb 16 | Feb 11 | Feb 3 |
| 16°F | Mar 5 | Feb 26 | Feb 21 | Feb 16 | Feb 11 | Feb 5 | Jan 31 | Jan 26 | Jan 18 |
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 15 | Oct 18 | Oct 20 | Oct 23 | Oct 25 | Oct 28 | Oct 31 | Nov 4 |
| 32°F | Oct 20 | Oct 24 | Oct 27 | Oct 31 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 15 |
| 28°F | Oct 30 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 15 | Nov 18 | Nov 23 | Nov 30 |
| 24°F | Nov 6 | Nov 12 | Nov 16 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 6 | Dec 14 |
| 20°F | Nov 15 | Nov 23 | Nov 28 | Dec 2 | Dec 6 | Dec 10 | Dec 15 | Dec 22 | Dec 29 |
| 16°F | Dec 1 | Dec 6 | Dec 11 | Dec 18 | Dec 24 | Dec 29 | Jan 2 | Jan 8 | Jan 18 |
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 | 203 | 198 | 194 | 189 | 185 | 181 | 175 | 169 |
| 32°F | 233 | 225 | 219 | 215 | 211 | 206 | 201 | 196 | 190 |
| 28°F | 258 | 250 | 244 | 238 | 232 | 227 | 223 | 217 | 209 |
| 24°F | 287 | 276 | 270 | 264 | 259 | 254 | 248 | 242 | 233 |
| 20°F | 316 | 305 | 297 | 292 | 286 | 280 | 274 | 266 | 258 |
| 16°F | 340 | 332 | 325 | 318 | 311 | 305 | 299 | 292 | 281 |
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
- 3,642
- Cooling degree days, base 65°F
- 1,728
- Growing degree days, base 40°F
- 7,644
- Growing degree days, base 45°F
- 6,167
- Growing degree days, base 50°F
- 4,827
- Growing degree days, base 55°F
- 3,639
- Growing degree days, base 60°F
- 2,609
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 835 | 0 | 25 |
| February | 660 | 1 | 38 |
| March | 471 | 6 | 126 |
| April | 212 | 38 | 301 |
| May | 56 | 155 | 565 |
| June | 1 | 342 | 790 |
| July | 0 | 446 | 911 |
| August | 0 | 431 | 896 |
| September | 17 | 251 | 684 |
| October | 182 | 54 | 351 |
| November | 472 | 4 | 103 |
| December | 735 | 1 | 38 |
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 1.4 km from Spring Hill. 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 USC00408953 (Thompson Stn). Public domain.