Antioch Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Antioch Pumping Plt #3. 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 19, a growing season of about 343 days.
- Median at 36°F
- last February 8, first December 4
- Median at 32°F
- last January 12, first December 19
- Median at 28°F
- last January 2, first December 29
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 12 | Mar 3 | Feb 23 | Feb 14 | Feb 8 | Feb 3 | Jan 29 | Jan 21 | Jan 11 |
| 32°F | Feb 1 | Jan 28 | Jan 22 | Jan 16 | Jan 12 | Jan 7 | Jan 2 | Dec 29 | Dec 20 |
| 28°F | Jan 22 | Jan 15 | Jan 10 | Jan 5 | Jan 2 | Dec 30 | Dec 28 | Dec 23 | Dec 16 |
| 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 18 | Nov 24 | Nov 29 | Dec 1 | Dec 4 | Dec 8 | Dec 12 | Dec 17 | Dec 28 |
| 32°F | Nov 29 | Dec 5 | Dec 10 | Dec 15 | Dec 19 | Dec 23 | Dec 29 | Jan 3 | Jan 12 |
| 28°F | Dec 9 | Dec 18 | Dec 22 | Dec 27 | Dec 29 | Jan 1 | Jan 4 | 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 | 331 | 320 | 311 | 305 | 299 | 291 | 284 | 274 | 263 |
| 32°F | 365 | 362 | 355 | 348 | 343 | 338 | 333 | 326 | 315 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 361 | 355 | 347 |
| 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
- 81% of years
- 28°F or colder
- 35% of years
- 24°F or colder
- 5% 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
- 2,230
- Cooling degree days, base 65°F
- 1,345
- Growing degree days, base 40°F
- 8,249
- Growing degree days, base 45°F
- 6,470
- Growing degree days, base 50°F
- 4,827
- Growing degree days, base 55°F
- 3,420
- Growing degree days, base 60°F
- 2,266
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 527 | 0 | 33 |
| February | 354 | 0 | 92 |
| March | 264 | 2 | 209 |
| April | 150 | 24 | 325 |
| May | 52 | 103 | 516 |
| June | 6 | 236 | 679 |
| July | 0 | 341 | 806 |
| August | 0 | 318 | 783 |
| September | 4 | 235 | 681 |
| October | 58 | 84 | 491 |
| November | 291 | 3 | 177 |
| December | 524 | 0 | 35 |
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 5.3 km from Antioch. 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 USC00040232 (Antioch Pumping Plt #3). Public domain.