Dalton Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Chatsworth 2. 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 2 and the first fall freeze around November 1, a growing season of about 212 days.
- Median at 36°F
- last April 15, first October 24
- Median at 32°F
- last April 2, first November 1
- Median at 28°F
- last March 19, 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 2 | Apr 28 | Apr 24 | Apr 20 | Apr 15 | Apr 11 | Apr 7 | Apr 3 | Mar 29 |
| 32°F | Apr 21 | Apr 13 | Apr 9 | Apr 5 | Apr 2 | Mar 31 | Mar 26 | Mar 20 | Mar 14 |
| 28°F | Apr 6 | Mar 31 | Mar 26 | Mar 22 | Mar 19 | Mar 15 | Mar 10 | Mar 4 | Feb 26 |
| 24°F | Mar 24 | Mar 18 | Mar 14 | Mar 8 | Mar 3 | Feb 28 | Feb 23 | Feb 15 | Feb 5 |
| 20°F | Mar 13 | Mar 6 | Feb 28 | Feb 20 | Feb 15 | Feb 10 | Feb 3 | Jan 29 | Jan 18 |
| 16°F | Mar 2 | Feb 19 | Feb 9 | Feb 3 | Jan 31 | Jan 27 | Jan 20 | Jan 14 | 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 11 | Oct 16 | Oct 19 | Oct 22 | Oct 24 | Oct 26 | Oct 29 | Nov 1 | Nov 5 |
| 32°F | Oct 21 | Oct 25 | Oct 28 | Oct 31 | Nov 1 | Nov 4 | Nov 6 | Nov 10 | Nov 17 |
| 28°F | Oct 30 | Nov 2 | Nov 5 | Nov 10 | Nov 13 | Nov 16 | Nov 21 | Nov 27 | Dec 4 |
| 24°F | Nov 8 | Nov 14 | Nov 18 | Nov 24 | Nov 28 | Dec 1 | Dec 6 | Dec 12 | Dec 23 |
| 20°F | Nov 18 | Nov 27 | Dec 2 | Dec 6 | Dec 12 | Dec 20 | Dec 28 | Jan 4 | Jan 12 |
| 16°F | Dec 3 | Dec 14 | Dec 23 | Dec 31 | Jan 2 | Jan 7 | Jan 13 | Jan 19 | Jan 29 |
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 | 211 | 204 | 198 | 193 | 189 | 185 | 181 | 175 | 168 |
| 32°F | 239 | 230 | 224 | 218 | 212 | 208 | 204 | 198 | 190 |
| 28°F | 267 | 257 | 251 | 245 | 240 | 235 | 228 | 222 | 214 |
| 24°F | 303 | 291 | 283 | 276 | 270 | 264 | 257 | 249 | 239 |
| 20°F | 337 | 327 | 317 | 309 | 303 | 296 | 289 | 280 | 268 |
| 16°F | 365 | 355 | 345 | 337 | 333 | 326 | 319 | 308 | 300 |
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
- 99% of years
- 16°F or colder
- 89% 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
- 3,346
- Cooling degree days, base 65°F
- 1,566
- Growing degree days, base 40°F
- 7,616
- Growing degree days, base 45°F
- 6,087
- Growing degree days, base 50°F
- 4,714
- Growing degree days, base 55°F
- 3,504
- Growing degree days, base 60°F
- 2,456
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 761 | 0 | 34 |
| February | 590 | 1 | 41 |
| March | 427 | 6 | 135 |
| April | 201 | 37 | 303 |
| May | 56 | 131 | 542 |
| June | 2 | 305 | 753 |
| July | 0 | 417 | 882 |
| August | 0 | 392 | 857 |
| September | 15 | 225 | 660 |
| October | 171 | 47 | 354 |
| November | 449 | 5 | 108 |
| December | 675 | 1 | 45 |
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 18.8 km from Dalton. 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 USC00091863 (Chatsworth 2). Public domain.