Cypress Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Fullerton Muni AP. 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 7 percent of years at Fullerton Muni AP, so there is no typical freeze season.
- Median at 36°F
- last January 4, 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 8 | Jan 25 | Jan 15 | Jan 8 | Jan 4 | Dec 31 | Dec 25 | Dec 19 | Dec 13 |
| 32°F | – | – | – | – | – | – | – | – | – |
| 28°F | – | – | – | – | – | – | – | – | – |
| 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 | Dec 7 | Dec 12 | Dec 16 | Dec 19 | Dec 24 | Dec 27 | Jan 1 | Jan 7 | Jan 20 |
| 32°F | – | – | – | – | – | – | – | – | – |
| 28°F | – | – | – | – | – | – | – | – | – |
| 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 | 365 | 365 | 363 | 357 | 352 | 345 | 338 | 325 |
| 32°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 |
| 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
- 63% of years
- 32°F or colder
- 7% of years
- 28°F or colder
- 0% of years
- 24°F or colder
- 0% 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
- 1,051
- Cooling degree days, base 65°F
- 1,507
- Growing degree days, base 40°F
- 9,581
- Growing degree days, base 45°F
- 7,757
- Growing degree days, base 50°F
- 5,940
- Growing degree days, base 55°F
- 4,201
- Growing degree days, base 60°F
- 2,684
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 235 | 5 | 239 |
| February | 187 | 10 | 244 |
| March | 138 | 22 | 349 |
| April | 78 | 48 | 420 |
| May | 27 | 86 | 524 |
| June | 2 | 176 | 624 |
| July | 0 | 318 | 783 |
| August | 0 | 358 | 823 |
| September | 1 | 300 | 750 |
| October | 16 | 150 | 598 |
| November | 113 | 33 | 371 |
| December | 254 | 2 | 216 |
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 8.1 km from Cypress. 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 USW00003166 (Fullerton Muni AP). Public domain.