Maricopa Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Taft. 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 24 and the first fall freeze around December 17, a growing season of about 330 days.
- Median at 36°F
- last February 26, first December 3
- Median at 32°F
- last January 24, first December 17
- 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 8 | Mar 29 | Mar 18 | Mar 5 | Feb 26 | Feb 18 | Feb 7 | Jan 31 | Jan 22 |
| 32°F | Mar 12 | Feb 23 | Feb 8 | Jan 31 | Jan 24 | Jan 17 | Jan 10 | Jan 2 | Dec 25 |
| 28°F | Feb 13 | Jan 25 | Jan 14 | Jan 7 | Jan 3 | Dec 31 | Dec 29 | Dec 23 | 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 23 | Nov 27 | Nov 30 | Dec 3 | Dec 6 | Dec 10 | Dec 15 | Dec 24 |
| 32°F | Dec 1 | Dec 5 | Dec 10 | Dec 13 | Dec 17 | Dec 23 | Dec 29 | Jan 4 | Jan 15 |
| 28°F | Dec 6 | Dec 12 | Dec 18 | Dec 23 | Dec 27 | Dec 31 | Jan 3 | Jan 10 | 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 | 318 | 305 | 295 | 286 | 277 | 267 | 257 | 246 | 233 |
| 32°F | 363 | 351 | 343 | 336 | 330 | 323 | 312 | 299 | 279 |
| 28°F | 365 | 365 | 365 | 365 | 365 | 362 | 356 | 349 | 336 |
| 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
- 44% of years
- 24°F or colder
- 4% 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
- 1,935
- Cooling degree days, base 65°F
- 2,206
- Growing degree days, base 40°F
- 9,401
- Growing degree days, base 45°F
- 7,612
- Growing degree days, base 50°F
- 5,940
- Growing degree days, base 55°F
- 4,462
- Growing degree days, base 60°F
- 3,222
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 471 | 0 | 67 |
| February | 324 | 1 | 120 |
| March | 199 | 19 | 292 |
| April | 125 | 59 | 386 |
| May | 33 | 195 | 628 |
| June | 4 | 340 | 786 |
| July | 0 | 565 | 1,031 |
| August | 0 | 524 | 989 |
| September | 1 | 368 | 817 |
| October | 48 | 127 | 544 |
| November | 254 | 7 | 216 |
| December | 476 | 0 | 65 |
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 10.5 km from Maricopa. 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 USC00048752 (Taft). Public domain.