Coosada Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Montgomery 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 13 and the first fall freeze around November 13, a growing season of about 244 days.
- Median at 36°F
- last March 29, first November 3
- Median at 32°F
- last March 13, first November 13
- Median at 28°F
- last February 27, first November 25
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 16 | Apr 10 | Apr 5 | Apr 1 | Mar 29 | Mar 24 | Mar 19 | Mar 14 | Mar 5 |
| 32°F | Mar 31 | Mar 25 | Mar 20 | Mar 16 | Mar 13 | Mar 8 | Mar 4 | Feb 28 | Feb 20 |
| 28°F | Mar 19 | Mar 14 | Mar 8 | Mar 3 | Feb 27 | Feb 21 | Feb 15 | Feb 8 | Jan 30 |
| 24°F | Mar 7 | Feb 28 | Feb 21 | Feb 14 | Feb 7 | Feb 2 | Jan 28 | Jan 20 | Jan 9 |
| 20°F | Feb 23 | Feb 9 | Feb 3 | Jan 31 | Jan 26 | Jan 20 | Jan 13 | Jan 5 | Dec 28 |
| 16°F | Feb 8 | Feb 2 | Jan 29 | Jan 23 | Jan 18 | Jan 13 | Jan 8 | Jan 3 | Dec 25 |
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 21 | Oct 26 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 18 |
| 32°F | Oct 31 | Nov 3 | Nov 6 | Nov 10 | Nov 13 | Nov 16 | Nov 19 | Nov 23 | Dec 1 |
| 28°F | Nov 8 | Nov 14 | Nov 18 | Nov 22 | Nov 25 | Nov 29 | Dec 3 | Dec 10 | Dec 24 |
| 24°F | Nov 17 | Nov 25 | Dec 1 | Dec 6 | Dec 14 | Dec 24 | Jan 1 | Jan 6 | Jan 16 |
| 20°F | Dec 1 | Dec 9 | Dec 22 | Dec 30 | Jan 2 | Jan 6 | Jan 12 | Jan 20 | Feb 1 |
| 16°F | Dec 15 | Dec 29 | Jan 2 | Jan 6 | Jan 10 | Jan 14 | Jan 19 | Jan 26 | Feb 2 |
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 | 244 | 236 | 230 | 225 | 220 | 215 | 211 | 206 | 198 |
| 32°F | 271 | 262 | 255 | 249 | 244 | 240 | 235 | 229 | 220 |
| 28°F | 305 | 293 | 284 | 277 | 272 | 265 | 259 | 253 | 244 |
| 24°F | 343 | 329 | 320 | 312 | 306 | 299 | 290 | 280 | 265 |
| 20°F | 365 | 365 | 355 | 345 | 338 | 332 | 325 | 316 | 301 |
| 16°F | 365 | 365 | 365 | 365 | 365 | 365 | 353 | 344 | 332 |
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
- 97% of years
- 20°F or colder
- 78% of years
- 16°F or colder
- 41% 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
- 2,000
- Cooling degree days, base 65°F
- 2,540
- Growing degree days, base 40°F
- 9,726
- Growing degree days, base 45°F
- 8,010
- Growing degree days, base 50°F
- 6,413
- Growing degree days, base 55°F
- 4,961
- Growing degree days, base 60°F
- 3,666
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 526 | 4 | 97 |
| February | 359 | 10 | 144 |
| March | 218 | 38 | 306 |
| April | 75 | 96 | 473 |
| May | 9 | 277 | 733 |
| June | 0 | 457 | 907 |
| July | 0 | 555 | 1,020 |
| August | 0 | 542 | 1,007 |
| September | 2 | 386 | 834 |
| October | 71 | 143 | 540 |
| November | 277 | 24 | 230 |
| December | 464 | 7 | 122 |
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 23.2 km from Coosada. 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 USW00013895 (Montgomery AP). Public domain.