Vineyard Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Sacramento 5 Ese. 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 12 and the first fall freeze around December 16, a growing season of about 341 days.
- Median at 36°F
- last February 12, first December 1
- Median at 32°F
- last January 12, first December 16
- Median at 28°F
- last December 31, first December 25
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 11 | Mar 2 | Feb 26 | Feb 19 | Feb 12 | Feb 6 | Jan 31 | Jan 22 | Jan 9 |
| 32°F | Feb 8 | Jan 31 | Jan 22 | Jan 16 | Jan 12 | Jan 4 | Dec 31 | Dec 25 | Dec 18 |
| 28°F | Jan 22 | Jan 13 | Jan 5 | Jan 2 | Dec 31 | Dec 29 | Dec 24 | Dec 20 | 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 15 | Nov 20 | Nov 24 | Nov 27 | Dec 1 | Dec 4 | Dec 8 | Dec 15 | Dec 29 |
| 32°F | Nov 28 | Dec 3 | Dec 7 | Dec 12 | Dec 16 | Dec 20 | Dec 28 | Jan 2 | Jan 14 |
| 28°F | Dec 5 | Dec 13 | Dec 16 | Dec 21 | Dec 25 | Dec 30 | Jan 1 | Jan 5 | Jan 14 |
| 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 | 328 | 315 | 305 | 297 | 289 | 283 | 277 | 269 | 260 |
| 32°F | 365 | 362 | 353 | 346 | 341 | 334 | 329 | 320 | 308 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 359 | 348 |
| 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
- 99% of years
- 32°F or colder
- 81% of years
- 28°F or colder
- 25% of years
- 24°F or colder
- 1% 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
- 2,138
- Cooling degree days, base 65°F
- 1,576
- Growing degree days, base 40°F
- 8,568
- Growing degree days, base 45°F
- 6,778
- Growing degree days, base 50°F
- 5,115
- Growing degree days, base 55°F
- 3,693
- Growing degree days, base 60°F
- 2,520
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 502 | 0 | 38 |
| February | 338 | 0 | 105 |
| March | 245 | 4 | 232 |
| April | 140 | 32 | 343 |
| May | 45 | 127 | 547 |
| June | 5 | 271 | 716 |
| July | 0 | 400 | 865 |
| August | 0 | 380 | 845 |
| September | 3 | 275 | 722 |
| October | 58 | 86 | 493 |
| November | 293 | 2 | 173 |
| December | 510 | 0 | 38 |
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 11.8 km from Vineyard. 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 USW00023271 (Sacramento 5 Ese). Public domain.