Doolittle Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Edinburg. A median date has an even chance of a later freeze in spring, or an earlier one in fall.
A freeze (32°F or colder) happens in only 40 percent of years at Edinburg, so there is no typical freeze season.
- Median at 36°F
- last January 25, first December 27
- Median at 32°F
- last January 8, first January 2
- Median at 28°F
- last January 3, first January 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 | Mar 3 | Feb 20 | Feb 9 | Jan 31 | Jan 25 | Jan 17 | Jan 9 | Dec 31 | Dec 22 |
| 32°F | Feb 21 | Feb 5 | Jan 27 | Jan 20 | Jan 8 | Jan 4 | Dec 31 | Dec 25 | Dec 17 |
| 28°F | Feb 3 | Jan 22 | Jan 11 | Jan 5 | Jan 3 | Dec 31 | Dec 28 | Dec 23 | Dec 14 |
| 24°F | – | – | – | – | – | – | – | – | – |
| 20°F | – | – | – | – | – | – | – | – | – |
| 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 | Dec 1 | Dec 8 | Dec 14 | Dec 20 | Dec 27 | Jan 1 | Jan 5 | Jan 12 | Jan 29 |
| 32°F | Dec 11 | Dec 18 | Dec 24 | Dec 30 | Jan 2 | Jan 6 | Jan 12 | Jan 26 | Feb 6 |
| 28°F | Dec 13 | Dec 21 | Dec 26 | Dec 30 | Jan 1 | Jan 4 | Jan 10 | Jan 20 | Feb 2 |
| 24°F | – | – | – | – | – | – | – | – | – |
| 20°F | – | – | – | – | – | – | – | – | – |
| 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 | 365 | 361 | 352 | 344 | 337 | 329 | 319 | 307 | 292 |
| 32°F | 365 | 365 | 365 | 365 | 365 | 365 | 357 | 347 | 333 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
| 24°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
| 20°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
| 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
- 82% of years
- 32°F or colder
- 40% of years
- 28°F or colder
- 11% of years
- 24°F or colder
- 0% of years
- 20°F or colder
- 0% of years
- 16°F or colder
- 0% 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
- 625
- Cooling degree days, base 65°F
- 4,285
- Growing degree days, base 40°F
- 12,789
- Growing degree days, base 45°F
- 10,979
- Growing degree days, base 50°F
- 9,190
- Growing degree days, base 55°F
- 7,453
- Growing degree days, base 60°F
- 5,807
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 214 | 46 | 325 |
| February | 119 | 101 | 414 |
| March | 52 | 179 | 593 |
| April | 6 | 317 | 761 |
| May | 0 | 518 | 983 |
| June | 0 | 600 | 1,050 |
| July | 0 | 671 | 1,136 |
| August | 0 | 683 | 1,148 |
| September | 0 | 551 | 1,001 |
| October | 3 | 390 | 852 |
| November | 57 | 156 | 552 |
| December | 174 | 73 | 376 |
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 7.3 km from Doolittle. 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 USC00412758 (Edinburg). Public domain.