Hidalgo Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Mcallen. 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 48 percent of years at Mcallen, so there is no typical freeze season.
- Median at 36°F
- last January 27, first December 19
- Median at 32°F
- last January 9, first January 1
- Median at 28°F
- last January 4, first January 2
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 1 | Feb 18 | Feb 9 | Feb 2 | Jan 27 | Jan 18 | Jan 10 | Jan 2 | Dec 20 |
| 32°F | Feb 12 | Feb 4 | Jan 30 | Jan 19 | Jan 9 | Jan 3 | Dec 31 | Dec 24 | Dec 14 |
| 28°F | Feb 9 | Feb 1 | Jan 24 | Jan 8 | Jan 4 | Jan 1 | Dec 27 | Dec 20 | Dec 15 |
| 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 | Nov 27 | Dec 3 | Dec 8 | Dec 13 | Dec 19 | Dec 25 | Jan 1 | Jan 9 | Jan 26 |
| 32°F | Dec 8 | Dec 14 | Dec 22 | Dec 28 | Jan 1 | Jan 5 | Jan 13 | Jan 26 | Feb 4 |
| 28°F | Dec 14 | Dec 18 | Dec 25 | Dec 30 | Jan 2 | Jan 6 | Jan 21 | Jan 31 | Feb 6 |
| 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 | 356 | 347 | 338 | 330 | 322 | 313 | 304 | 289 |
| 32°F | 365 | 365 | 365 | 365 | 365 | 357 | 348 | 338 | 324 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 354 |
| 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
- 87% of years
- 32°F or colder
- 48% of years
- 28°F or colder
- 16% of years
- 24°F or colder
- 3% 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
- 594
- Cooling degree days, base 65°F
- 4,437
- Growing degree days, base 40°F
- 12,971
- Growing degree days, base 45°F
- 11,158
- Growing degree days, base 50°F
- 9,366
- Growing degree days, base 55°F
- 7,622
- Growing degree days, base 60°F
- 5,970
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 196 | 53 | 344 |
| February | 103 | 97 | 422 |
| March | 44 | 209 | 633 |
| April | 8 | 341 | 783 |
| May | 0 | 512 | 977 |
| June | 0 | 630 | 1,080 |
| July | 0 | 685 | 1,150 |
| August | 0 | 711 | 1,176 |
| September | 0 | 561 | 1,011 |
| October | 4 | 399 | 860 |
| November | 64 | 167 | 555 |
| December | 175 | 72 | 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 10.3 km from Hidalgo. 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 USC00415701 (Mcallen). Public domain.