Salado Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Stillhouse Hollow Dam. 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 14 and the first fall freeze around November 20, a growing season of about 251 days.
- Median at 36°F
- last March 27, first November 8
- Median at 32°F
- last March 14, first November 20
- Median at 28°F
- last March 1, first December 1
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 19 | Apr 9 | Apr 4 | Apr 2 | Mar 27 | Mar 23 | Mar 19 | Mar 14 | Mar 7 |
| 32°F | Apr 4 | Mar 29 | Mar 22 | Mar 17 | Mar 14 | Mar 10 | Mar 5 | Feb 28 | Feb 22 |
| 28°F | Mar 21 | Mar 14 | Mar 9 | Mar 4 | Mar 1 | Feb 25 | Feb 20 | Feb 12 | Jan 31 |
| 24°F | Mar 10 | Mar 3 | Feb 25 | Feb 19 | Feb 12 | Feb 4 | Jan 30 | Jan 22 | Jan 9 |
| 20°F | Mar 1 | Feb 19 | Feb 11 | Feb 3 | Jan 30 | Jan 22 | Jan 14 | Jan 3 | Dec 22 |
| 16°F | Feb 17 | Feb 9 | Feb 5 | Jan 31 | Jan 23 | Jan 19 | Jan 12 | Jan 3 | Dec 24 |
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 29 | Nov 1 | Nov 5 | Nov 8 | Nov 12 | Nov 17 | Nov 22 | Nov 28 |
| 32°F | Oct 29 | Nov 5 | Nov 11 | Nov 15 | Nov 20 | Nov 24 | Nov 28 | Dec 3 | Dec 9 |
| 28°F | Nov 10 | Nov 18 | Nov 23 | Nov 28 | Dec 1 | Dec 6 | Dec 12 | Dec 20 | Dec 28 |
| 24°F | Nov 23 | Dec 1 | Dec 8 | Dec 15 | Dec 21 | Dec 26 | Jan 2 | Jan 10 | Jan 24 |
| 20°F | Dec 5 | Dec 15 | Dec 23 | Dec 30 | Jan 3 | Jan 9 | Jan 17 | Jan 29 | Feb 7 |
| 16°F | Dec 17 | Dec 29 | Jan 3 | Jan 7 | Jan 13 | Jan 18 | Jan 29 | Feb 3 | Feb 10 |
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 | 251 | 244 | 237 | 231 | 226 | 220 | 215 | 208 | 197 |
| 32°F | 276 | 268 | 261 | 255 | 251 | 245 | 239 | 231 | 218 |
| 28°F | 311 | 300 | 291 | 284 | 277 | 271 | 264 | 256 | 247 |
| 24°F | 349 | 336 | 327 | 319 | 309 | 303 | 295 | 285 | 274 |
| 20°F | 365 | 365 | 365 | 355 | 346 | 338 | 329 | 319 | 305 |
| 16°F | 365 | 365 | 365 | 365 | 365 | 365 | 363 | 349 | 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
- 95% of years
- 20°F or colder
- 68% of years
- 16°F or colder
- 31% 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
- 2,032
- Cooling degree days, base 65°F
- 2,630
- Growing degree days, base 40°F
- 9,803
- Growing degree days, base 45°F
- 8,098
- Growing degree days, base 50°F
- 6,498
- Growing degree days, base 55°F
- 5,049
- Growing degree days, base 60°F
- 3,755
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 534 | 3 | 86 |
| February | 379 | 8 | 132 |
| March | 237 | 31 | 291 |
| April | 74 | 101 | 480 |
| May | 10 | 275 | 730 |
| June | 0 | 461 | 910 |
| July | 0 | 578 | 1,043 |
| August | 0 | 586 | 1,051 |
| September | 3 | 390 | 837 |
| October | 62 | 163 | 569 |
| November | 254 | 29 | 261 |
| December | 478 | 6 | 109 |
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 10.1 km from Salado. 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 USC00418646 (Stillhouse Hollow Dam). Public domain.