Schulter Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Okmulgee Wtr Wks. 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 April 8 and the first fall freeze around October 28, a growing season of about 203 days.
- Median at 36°F
- last April 19, first October 20
- Median at 32°F
- last April 8, first October 28
- Median at 28°F
- last March 29, first November 6
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 | May 3 | Apr 29 | Apr 25 | Apr 23 | Apr 19 | Apr 15 | Apr 12 | Apr 8 | Mar 31 |
| 32°F | Apr 25 | Apr 20 | Apr 14 | Apr 11 | Apr 8 | Apr 5 | Apr 1 | Mar 28 | Mar 23 |
| 28°F | Apr 15 | Apr 8 | Apr 5 | Apr 1 | Mar 29 | Mar 25 | Mar 21 | Mar 16 | Mar 11 |
| 24°F | Apr 3 | Mar 27 | Mar 23 | Mar 19 | Mar 15 | Mar 12 | Mar 8 | Mar 4 | Feb 28 |
| 20°F | Mar 19 | Mar 14 | Mar 10 | Mar 6 | Mar 4 | Mar 1 | Feb 27 | Feb 23 | Feb 15 |
| 16°F | Mar 11 | Mar 5 | Mar 2 | Feb 28 | Feb 23 | Feb 19 | Feb 13 | Feb 5 | Jan 25 |
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 | Oct 5 | Oct 9 | Oct 13 | Oct 17 | Oct 20 | Oct 22 | Oct 25 | Oct 29 | Nov 2 |
| 32°F | Oct 12 | Oct 19 | Oct 23 | Oct 26 | Oct 28 | Oct 31 | Nov 3 | Nov 6 | Nov 11 |
| 28°F | Oct 22 | Oct 28 | Oct 31 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 18 | Nov 23 |
| 24°F | Oct 31 | Nov 5 | Nov 9 | Nov 12 | Nov 17 | Nov 22 | Nov 25 | Nov 30 | Dec 4 |
| 20°F | Nov 8 | Nov 15 | Nov 21 | Nov 25 | Nov 29 | Dec 2 | Dec 5 | Dec 10 | Dec 16 |
| 16°F | Nov 21 | Nov 28 | Dec 3 | Dec 6 | Dec 11 | Dec 16 | Dec 21 | Dec 30 | Jan 8 |
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 | 204 | 196 | 192 | 188 | 184 | 179 | 175 | 170 | 164 |
| 32°F | 224 | 217 | 211 | 207 | 203 | 199 | 195 | 188 | 181 |
| 28°F | 247 | 240 | 234 | 229 | 224 | 220 | 214 | 210 | 200 |
| 24°F | 271 | 263 | 256 | 249 | 245 | 240 | 235 | 229 | 221 |
| 20°F | 295 | 285 | 279 | 274 | 270 | 264 | 259 | 252 | 244 |
| 16°F | 320 | 311 | 304 | 299 | 292 | 287 | 280 | 274 | 266 |
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
- 100% of years
- 28°F or colder
- 100% of years
- 24°F or colder
- 100% of years
- 20°F or colder
- 100% of years
- 16°F or colder
- 100% 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
- 3,599
- Cooling degree days, base 65°F
- 1,812
- Growing degree days, base 40°F
- 7,728
- Growing degree days, base 45°F
- 6,246
- Growing degree days, base 50°F
- 4,917
- Growing degree days, base 55°F
- 3,734
- Growing degree days, base 60°F
- 2,701
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 839 | 0 | 16 |
| February | 653 | 0 | 27 |
| March | 443 | 8 | 135 |
| April | 201 | 39 | 306 |
| May | 49 | 141 | 557 |
| June | 2 | 350 | 798 |
| July | 0 | 513 | 978 |
| August | 0 | 464 | 928 |
| September | 21 | 237 | 666 |
| October | 176 | 55 | 360 |
| November | 468 | 6 | 122 |
| December | 749 | 0 | 25 |
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 13.6 km from Schulter. 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 USC00346670 (Okmulgee Wtr Wks). Public domain.