Nicholls Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Alma Bacon CO AP. 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 11 and the first fall freeze around November 20, a growing season of about 256 days.
- Median at 36°F
- last March 24, first November 9
- Median at 32°F
- last March 11, first November 20
- Median at 28°F
- last February 21, first December 7
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 13 | Apr 6 | Apr 2 | Mar 28 | Mar 24 | Mar 20 | Mar 17 | Mar 13 | Mar 5 |
| 32°F | Mar 30 | Mar 23 | Mar 19 | Mar 15 | Mar 11 | Mar 7 | Mar 2 | Feb 26 | Feb 17 |
| 28°F | Mar 16 | Mar 10 | Mar 3 | Feb 27 | Feb 21 | Feb 15 | Feb 8 | Jan 31 | Jan 20 |
| 24°F | Mar 3 | Feb 23 | Feb 13 | Feb 7 | Feb 1 | Jan 28 | Jan 21 | Jan 12 | Jan 1 |
| 20°F | Feb 22 | Feb 11 | Feb 5 | Jan 30 | Jan 25 | Jan 17 | Jan 9 | Jan 2 | Dec 25 |
| 16°F | Feb 15 | Feb 8 | Feb 3 | Feb 1 | Jan 28 | Jan 20 | Jan 16 | Jan 11 | Jan 4 |
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 27 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 11 | Nov 15 | Nov 18 | Nov 24 |
| 32°F | Nov 5 | Nov 10 | Nov 14 | Nov 17 | Nov 20 | Nov 24 | Nov 29 | Dec 3 | Dec 12 |
| 28°F | Nov 16 | Nov 22 | Nov 28 | Dec 2 | Dec 7 | Dec 15 | Dec 23 | Jan 1 | Jan 11 |
| 24°F | Nov 28 | Dec 5 | Dec 13 | Dec 23 | Dec 31 | Jan 4 | Jan 10 | Jan 19 | Feb 1 |
| 20°F | Dec 13 | Dec 25 | Jan 1 | Jan 6 | Jan 11 | Jan 17 | Jan 26 | Feb 2 | Feb 10 |
| 16°F | Jan 3 | Jan 9 | Jan 14 | Jan 18 | Jan 24 | Jan 31 | Feb 3 | Feb 7 | Feb 14 |
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 | 256 | 246 | 240 | 235 | 229 | 224 | 218 | 212 | 204 |
| 32°F | 287 | 276 | 269 | 262 | 256 | 251 | 245 | 240 | 230 |
| 28°F | 330 | 314 | 305 | 300 | 292 | 285 | 276 | 268 | 257 |
| 24°F | 365 | 351 | 342 | 335 | 328 | 319 | 310 | 303 | 290 |
| 20°F | 365 | 365 | 365 | 365 | 362 | 351 | 341 | 331 | 318 |
| 16°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 343 |
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
- 86% of years
- 20°F or colder
- 50% of years
- 16°F or colder
- 14% 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
- 1,645
- Cooling degree days, base 65°F
- 2,542
- Growing degree days, base 40°F
- 10,051
- Growing degree days, base 45°F
- 8,294
- Growing degree days, base 50°F
- 6,629
- Growing degree days, base 55°F
- 5,103
- Growing degree days, base 60°F
- 3,732
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 442 | 7 | 134 |
| February | 310 | 13 | 171 |
| March | 189 | 38 | 330 |
| April | 61 | 106 | 496 |
| May | 6 | 290 | 749 |
| June | 0 | 450 | 900 |
| July | 0 | 539 | 1,004 |
| August | 0 | 519 | 984 |
| September | 1 | 376 | 825 |
| October | 46 | 159 | 579 |
| November | 214 | 34 | 287 |
| December | 377 | 12 | 170 |
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 12.3 km from Nicholls. 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 USW00013870 (Alma Bacon CO AP). Public domain.