Hughson Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Turlock #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 January 6 and the first fall freeze around December 20, a growing season of about 351 days.
- Median at 36°F
- last January 31, first December 7
- Median at 32°F
- last January 6, first December 20
- Median at 28°F
- last December 30, first December 24
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 | Feb 26 | Feb 19 | Feb 11 | Feb 5 | Jan 31 | Jan 26 | Jan 21 | Jan 13 | Jan 2 |
| 32°F | Jan 31 | Jan 24 | Jan 16 | Jan 11 | Jan 6 | Jan 1 | Dec 29 | Dec 23 | Dec 14 |
| 28°F | Jan 20 | Jan 13 | Jan 7 | Jan 3 | Dec 30 | Dec 26 | Dec 23 | Dec 17 | Dec 10 |
| 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 21 | Nov 26 | Dec 1 | Dec 4 | Dec 7 | Dec 11 | Dec 15 | Dec 22 | Jan 3 |
| 32°F | Dec 3 | Dec 8 | Dec 11 | Dec 17 | Dec 20 | Dec 26 | Dec 31 | Jan 6 | Jan 16 |
| 28°F | Dec 8 | Dec 15 | Dec 19 | Dec 21 | Dec 24 | Dec 30 | Jan 3 | Jan 10 | Jan 16 |
| 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 | 345 | 335 | 327 | 319 | 312 | 306 | 299 | 290 | 279 |
| 32°F | 365 | 365 | 363 | 357 | 351 | 346 | 340 | 334 | 325 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 363 | 351 |
| 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
- 98% of years
- 32°F or colder
- 68% of years
- 28°F or colder
- 20% of years
- 24°F or colder
- 2% 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
- 2,090
- Cooling degree days, base 65°F
- 1,750
- Growing degree days, base 40°F
- 8,792
- Growing degree days, base 45°F
- 7,008
- Growing degree days, base 50°F
- 5,351
- Growing degree days, base 55°F
- 3,915
- Growing degree days, base 60°F
- 2,719
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 510 | 0 | 42 |
| February | 329 | 0 | 112 |
| March | 232 | 6 | 244 |
| April | 126 | 38 | 362 |
| May | 35 | 150 | 580 |
| June | 3 | 306 | 753 |
| July | 0 | 446 | 911 |
| August | 0 | 412 | 877 |
| September | 2 | 296 | 744 |
| October | 53 | 93 | 505 |
| November | 286 | 3 | 180 |
| December | 513 | 0 | 41 |
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 10.7 km from Hughson. 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 USC00049073 (Turlock #2). Public domain.