Fritch Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Sanford Dam. 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 20 and the first fall freeze around October 25, a growing season of about 187 days.
- Median at 36°F
- last April 30, first October 15
- Median at 32°F
- last April 20, first October 25
- Median at 28°F
- last April 9, first November 1
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 15 | May 10 | May 6 | May 3 | Apr 30 | Apr 28 | Apr 25 | Apr 22 | Apr 17 |
| 32°F | May 4 | Apr 30 | Apr 27 | Apr 23 | Apr 20 | Apr 17 | Apr 14 | Apr 9 | Apr 5 |
| 28°F | Apr 26 | Apr 21 | Apr 16 | Apr 12 | Apr 9 | Apr 6 | Apr 3 | Mar 31 | Mar 24 |
| 24°F | Apr 17 | Apr 10 | Apr 6 | Apr 3 | Mar 31 | Mar 25 | Mar 21 | Mar 15 | Mar 9 |
| 20°F | Apr 4 | Mar 31 | Mar 23 | Mar 18 | Mar 13 | Mar 9 | Mar 6 | Mar 2 | Feb 25 |
| 16°F | Mar 23 | Mar 14 | Mar 9 | Mar 6 | Mar 2 | Feb 28 | Feb 24 | Feb 19 | Feb 11 |
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 1 | Oct 6 | Oct 10 | Oct 13 | Oct 15 | Oct 18 | Oct 20 | Oct 23 | Oct 26 |
| 32°F | Oct 11 | Oct 16 | Oct 20 | Oct 22 | Oct 25 | Oct 27 | Oct 29 | Nov 1 | Nov 4 |
| 28°F | Oct 21 | Oct 25 | Oct 28 | Oct 31 | Nov 1 | Nov 3 | Nov 5 | Nov 8 | Nov 13 |
| 24°F | Oct 30 | Nov 1 | Nov 4 | Nov 7 | Nov 9 | Nov 12 | Nov 15 | Nov 20 | Nov 25 |
| 20°F | Nov 4 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 23 | Nov 26 | Nov 30 | Dec 4 |
| 16°F | Nov 12 | Nov 18 | Nov 22 | Nov 26 | Nov 29 | Dec 2 | Dec 6 | Dec 11 | Dec 18 |
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 | 186 | 179 | 175 | 171 | 167 | 162 | 158 | 153 | 146 |
| 32°F | 205 | 199 | 195 | 191 | 187 | 182 | 178 | 173 | 166 |
| 28°F | 227 | 219 | 215 | 210 | 206 | 202 | 196 | 191 | 184 |
| 24°F | 250 | 242 | 235 | 231 | 226 | 221 | 216 | 211 | 202 |
| 20°F | 272 | 264 | 258 | 252 | 248 | 243 | 238 | 232 | 223 |
| 16°F | 299 | 289 | 283 | 278 | 271 | 266 | 260 | 252 | 245 |
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
- 4,149
- Cooling degree days, base 65°F
- 1,739
- Growing degree days, base 40°F
- 7,283
- Growing degree days, base 45°F
- 5,866
- Growing degree days, base 50°F
- 4,609
- Growing degree days, base 55°F
- 3,511
- Growing degree days, base 60°F
- 2,557
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 877 | 0 | 7 |
| February | 716 | 0 | 22 |
| March | 527 | 4 | 97 |
| April | 279 | 24 | 243 |
| May | 88 | 136 | 517 |
| June | 5 | 357 | 802 |
| July | 0 | 499 | 964 |
| August | 1 | 441 | 905 |
| September | 31 | 230 | 650 |
| October | 221 | 45 | 317 |
| November | 554 | 2 | 76 |
| December | 851 | 0 | 9 |
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 8.7 km from Fritch. 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 USC00418040 (Sanford Dam). Public domain.