Fowler Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Fresno Yosemite Intl AP. 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 14 and the first fall freeze around December 14, a growing season of about 337 days.
- Median at 36°F
- last February 15, first December 1
- Median at 32°F
- last January 14, first December 14
- Median at 28°F
- last January 1, 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 | Mar 13 | Mar 2 | Feb 26 | Feb 21 | Feb 15 | Feb 9 | Feb 3 | Jan 28 | Jan 19 |
| 32°F | Feb 11 | Feb 2 | Jan 29 | Jan 21 | Jan 14 | Jan 9 | Jan 3 | Dec 31 | Dec 22 |
| 28°F | Jan 24 | Jan 15 | Jan 9 | Jan 5 | Jan 1 | Dec 30 | Dec 27 | Dec 21 | Dec 13 |
| 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 16 | Nov 21 | Nov 25 | Nov 28 | Dec 1 | Dec 3 | Dec 7 | Dec 13 | Dec 24 |
| 32°F | Nov 29 | Dec 2 | Dec 6 | Dec 10 | Dec 14 | Dec 20 | Dec 28 | Jan 3 | Jan 12 |
| 28°F | Dec 7 | Dec 11 | Dec 15 | Dec 19 | Dec 24 | Dec 29 | Jan 2 | Jan 7 | Jan 15 |
| 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 | 323 | 310 | 301 | 294 | 288 | 282 | 276 | 267 | 256 |
| 32°F | 365 | 358 | 348 | 342 | 337 | 332 | 324 | 316 | 305 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 360 | 351 | 343 |
| 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
- 100% of years
- 32°F or colder
- 85% of years
- 28°F or colder
- 33% of years
- 24°F or colder
- 4% 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
- 2,187
- Cooling degree days, base 65°F
- 2,209
- Growing degree days, base 40°F
- 9,155
- Growing degree days, base 45°F
- 7,386
- Growing degree days, base 50°F
- 5,768
- Growing degree days, base 55°F
- 4,363
- Growing degree days, base 60°F
- 3,186
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 527 | 0 | 38 |
| February | 356 | 0 | 96 |
| March | 242 | 6 | 239 |
| April | 129 | 48 | 370 |
| May | 32 | 191 | 625 |
| June | 3 | 382 | 830 |
| July | 0 | 573 | 1,038 |
| August | 0 | 533 | 998 |
| September | 2 | 364 | 811 |
| October | 57 | 108 | 516 |
| November | 299 | 3 | 175 |
| December | 541 | 0 | 33 |
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 17 km from Fowler. 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 USW00093193 (Fresno Yosemite Intl AP). Public domain.