Luttrell Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Jefferson City. 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 24 and the first fall freeze around October 17, a growing season of about 175 days.
- Median at 36°F
- last May 6, first October 10
- Median at 32°F
- last April 24, first October 17
- Median at 28°F
- last April 11, first October 27
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 21 | May 16 | May 12 | May 8 | May 6 | May 3 | Apr 30 | Apr 25 | Apr 21 |
| 32°F | May 13 | May 7 | May 2 | Apr 29 | Apr 24 | Apr 22 | Apr 19 | Apr 15 | Apr 10 |
| 28°F | May 1 | Apr 24 | Apr 19 | Apr 15 | Apr 11 | Apr 7 | Apr 5 | Apr 1 | Mar 28 |
| 24°F | Apr 19 | Apr 9 | Apr 5 | Apr 2 | Mar 31 | Mar 28 | Mar 24 | Mar 19 | Mar 13 |
| 20°F | Apr 3 | Mar 30 | Mar 26 | Mar 23 | Mar 19 | Mar 15 | Mar 10 | Mar 4 | Feb 24 |
| 16°F | Mar 26 | Mar 20 | Mar 15 | Mar 10 | Mar 5 | Feb 28 | Feb 21 | Feb 13 | Feb 3 |
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 | Sep 28 | Oct 3 | Oct 6 | Oct 8 | Oct 10 | Oct 13 | Oct 15 | Oct 18 | Oct 22 |
| 32°F | Oct 6 | Oct 10 | Oct 12 | Oct 15 | Oct 17 | Oct 20 | Oct 23 | Oct 27 | Nov 1 |
| 28°F | Oct 13 | Oct 17 | Oct 21 | Oct 24 | Oct 27 | Oct 29 | Nov 1 | Nov 4 | Nov 8 |
| 24°F | Oct 21 | Oct 26 | Oct 29 | Nov 1 | Nov 4 | Nov 6 | Nov 10 | Nov 15 | Nov 23 |
| 20°F | Oct 31 | Nov 4 | Nov 8 | Nov 12 | Nov 16 | Nov 21 | Nov 26 | Dec 1 | Dec 6 |
| 16°F | Nov 7 | Nov 15 | Nov 21 | Nov 27 | Dec 1 | Dec 5 | Dec 11 | Dec 20 | Dec 31 |
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 | 175 | 169 | 164 | 160 | 156 | 152 | 147 | 142 | 136 |
| 32°F | 196 | 189 | 183 | 179 | 175 | 170 | 166 | 158 | 151 |
| 28°F | 220 | 211 | 205 | 201 | 196 | 191 | 185 | 180 | 169 |
| 24°F | 244 | 237 | 230 | 224 | 219 | 214 | 208 | 203 | 195 |
| 20°F | 276 | 265 | 258 | 251 | 245 | 240 | 233 | 226 | 216 |
| 16°F | 309 | 296 | 288 | 280 | 274 | 267 | 260 | 251 | 240 |
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
- 4,338
- Cooling degree days, base 65°F
- 1,042
- Growing degree days, base 40°F
- 6,369
- Growing degree days, base 45°F
- 4,982
- Growing degree days, base 50°F
- 3,763
- Growing degree days, base 55°F
- 2,701
- Growing degree days, base 60°F
- 1,793
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 900 | 0 | 8 |
| February | 727 | 0 | 15 |
| March | 585 | 0 | 63 |
| April | 307 | 9 | 197 |
| May | 98 | 72 | 442 |
| June | 10 | 213 | 652 |
| July | 1 | 310 | 773 |
| August | 1 | 286 | 750 |
| September | 39 | 136 | 548 |
| October | 276 | 16 | 237 |
| November | 576 | 1 | 62 |
| December | 818 | 0 | 15 |
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 25.6 km from Luttrell. 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 USC00404613 (Jefferson City). Public domain.