Avondale Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Litchfield Park. 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 7 and the first fall freeze around December 24, a growing season of about 351 days.
- Median at 36°F
- last January 31, first December 9
- Median at 32°F
- last January 7, first December 24
- Median at 28°F
- last January 5, first January 4
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 24 | Feb 15 | Feb 9 | Feb 4 | Jan 31 | Jan 26 | Jan 20 | Jan 13 | Jan 4 |
| 32°F | Feb 5 | Jan 26 | Jan 18 | Jan 12 | Jan 7 | Jan 3 | Dec 30 | Dec 24 | Dec 17 |
| 28°F | Jan 22 | Jan 15 | Jan 11 | Jan 8 | Jan 5 | Jan 3 | Jan 1 | Dec 28 | Dec 21 |
| 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 24 | Nov 29 | Dec 3 | Dec 6 | Dec 9 | Dec 12 | Dec 16 | Dec 20 | Dec 28 |
| 32°F | Dec 6 | Dec 11 | Dec 16 | Dec 20 | Dec 24 | Dec 28 | Jan 1 | Jan 6 | Jan 16 |
| 28°F | Dec 18 | Dec 26 | Jan 1 | Jan 1 | Jan 4 | Jan 6 | Jan 10 | Jan 13 | Jan 21 |
| 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 | 343 | 335 | 326 | 319 | 313 | 308 | 302 | 294 | 285 |
| 32°F | 365 | 365 | 361 | 356 | 351 | 345 | 339 | 333 | 320 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 356 |
| 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
- 77% of years
- 28°F or colder
- 20% of years
- 24°F or colder
- 2% 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
- 1,140
- Cooling degree days, base 65°F
- 4,202
- Growing degree days, base 40°F
- 12,187
- Growing degree days, base 45°F
- 10,369
- Growing degree days, base 50°F
- 8,590
- Growing degree days, base 55°F
- 6,925
- Growing degree days, base 60°F
- 5,464
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 326 | 0 | 156 |
| February | 201 | 7 | 231 |
| March | 84 | 67 | 448 |
| April | 19 | 207 | 638 |
| May | 1 | 460 | 924 |
| June | 0 | 715 | 1,165 |
| July | 0 | 894 | 1,359 |
| August | 0 | 857 | 1,322 |
| September | 0 | 646 | 1,096 |
| October | 9 | 304 | 760 |
| November | 135 | 44 | 362 |
| December | 364 | 0 | 127 |
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 7.1 km from Avondale. 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 USC00024977 (Litchfield Park). Public domain.