Soquel Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Santa Cruz. 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 29 and the first fall freeze around December 13, a growing season of about 323 days.
- Median at 36°F
- last March 14, first November 24
- Median at 32°F
- last January 29, first December 13
- Median at 28°F
- last January 3, first December 27
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 | Apr 12 | Apr 5 | Mar 30 | Mar 23 | Mar 14 | Mar 7 | Feb 28 | Feb 18 | Feb 4 |
| 32°F | Feb 28 | Feb 19 | Feb 11 | Feb 3 | Jan 29 | Jan 19 | Jan 10 | Jan 2 | Dec 25 |
| 28°F | Jan 31 | Jan 21 | Jan 12 | Jan 7 | Jan 3 | Dec 30 | Dec 26 | Dec 21 | Dec 12 |
| 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 7 | Nov 13 | Nov 18 | Nov 21 | Nov 24 | Nov 29 | Dec 2 | Dec 7 | Dec 15 |
| 32°F | Nov 23 | Nov 30 | Dec 4 | Dec 8 | Dec 13 | Dec 19 | Dec 29 | Jan 5 | Jan 22 |
| 28°F | Dec 6 | Dec 10 | Dec 16 | Dec 21 | Dec 27 | Jan 1 | Jan 7 | Jan 14 | Jan 27 |
| 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 | 294 | 280 | 271 | 263 | 255 | 247 | 240 | 230 | 221 |
| 32°F | 361 | 349 | 340 | 333 | 323 | 314 | 305 | 294 | 278 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 364 | 357 | 348 | 337 |
| 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
- 91% of years
- 28°F or colder
- 42% 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
- 2,488
- Cooling degree days, base 65°F
- 180
- Growing degree days, base 40°F
- 6,817
- Growing degree days, base 45°F
- 5,003
- Growing degree days, base 50°F
- 3,271
- Growing degree days, base 55°F
- 1,789
- Growing degree days, base 60°F
- 728
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 405 | 0 | 92 |
| February | 328 | 0 | 109 |
| March | 301 | 1 | 173 |
| April | 229 | 4 | 227 |
| May | 159 | 10 | 316 |
| June | 85 | 19 | 384 |
| July | 51 | 30 | 443 |
| August | 38 | 44 | 471 |
| September | 54 | 48 | 444 |
| October | 125 | 23 | 363 |
| November | 285 | 2 | 176 |
| December | 428 | 0 | 73 |
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 3.8 km from Soquel. 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 USC00047916 (Santa Cruz). Public domain.