Newton Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Sam Rayburn 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 February 24 and the first fall freeze around December 1, a growing season of about 280 days.
- Median at 36°F
- last March 13, first November 19
- Median at 32°F
- last February 24, first December 1
- Median at 28°F
- last February 3, first December 22
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 4 | Mar 30 | Mar 24 | Mar 18 | Mar 13 | Mar 8 | Mar 1 | Feb 25 | Feb 17 |
| 32°F | Mar 23 | Mar 13 | Mar 6 | Feb 28 | Feb 24 | Feb 18 | Feb 12 | Feb 2 | Jan 28 |
| 28°F | Mar 5 | Feb 25 | Feb 18 | Feb 11 | Feb 3 | Jan 30 | Jan 25 | Jan 18 | Jan 7 |
| 24°F | Feb 24 | Feb 10 | Feb 1 | Jan 29 | Jan 23 | Jan 18 | Jan 11 | Jan 4 | Dec 27 |
| 20°F | Feb 7 | Feb 1 | Jan 29 | Jan 23 | Jan 19 | Jan 14 | Jan 8 | Jan 3 | Dec 30 |
| 16°F | – | – | – | – | – | – | – | – | – |
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 | Nov 1 | Nov 6 | Nov 10 | Nov 15 | Nov 19 | Nov 22 | Nov 26 | Dec 1 | Dec 6 |
| 32°F | Nov 9 | Nov 18 | Nov 23 | Nov 28 | Dec 1 | Dec 5 | Dec 9 | Dec 16 | Dec 27 |
| 28°F | Nov 26 | Dec 3 | Dec 8 | Dec 14 | Dec 22 | Dec 29 | Jan 2 | Jan 7 | Jan 21 |
| 24°F | Dec 11 | Dec 21 | Dec 29 | Jan 1 | Jan 5 | Jan 9 | Jan 15 | Jan 23 | Feb 4 |
| 20°F | Dec 28 | Jan 1 | Jan 4 | Jan 7 | Jan 12 | Jan 15 | Jan 19 | Jan 28 | Feb 2 |
| 16°F | – | – | – | – | – | – | – | – | – |
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 | 280 | 270 | 263 | 255 | 249 | 243 | 236 | 229 | 220 |
| 32°F | 316 | 303 | 293 | 286 | 280 | 274 | 266 | 258 | 248 |
| 28°F | 353 | 340 | 333 | 324 | 317 | 309 | 303 | 292 | 280 |
| 24°F | 365 | 365 | 365 | 362 | 353 | 345 | 337 | 330 | 313 |
| 20°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 360 | 344 |
| 16°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
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
- 94% of years
- 24°F or colder
- 62% of years
- 20°F or colder
- 22% of years
- 16°F or colder
- 2% 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
- 1,671
- Cooling degree days, base 65°F
- 2,988
- Growing degree days, base 40°F
- 10,475
- Growing degree days, base 45°F
- 8,732
- Growing degree days, base 50°F
- 7,086
- Growing degree days, base 55°F
- 5,568
- Growing degree days, base 60°F
- 4,195
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 454 | 11 | 133 |
| February | 318 | 22 | 180 |
| March | 181 | 64 | 367 |
| April | 60 | 145 | 537 |
| May | 5 | 338 | 798 |
| June | 0 | 509 | 958 |
| July | 0 | 601 | 1,066 |
| August | 0 | 603 | 1,068 |
| September | 2 | 444 | 892 |
| October | 46 | 190 | 611 |
| November | 207 | 47 | 312 |
| December | 399 | 15 | 163 |
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 40.5 km from Newton. 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 USC00417936 (Sam Rayburn Dam). Public domain.