Warsaw Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Wyoming 3W. 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 May 4 and the first fall freeze around October 17, a growing season of about 164 days.
- Median at 36°F
- last May 14, first October 6
- Median at 32°F
- last May 4, first October 17
- Median at 28°F
- last April 25, first October 30
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 27 | May 23 | May 20 | May 17 | May 14 | May 11 | May 8 | May 5 | Apr 30 |
| 32°F | May 19 | May 14 | May 10 | May 7 | May 4 | May 1 | Apr 29 | Apr 26 | Apr 22 |
| 28°F | May 8 | May 3 | May 1 | Apr 28 | Apr 25 | Apr 22 | Apr 19 | Apr 16 | Apr 11 |
| 24°F | Apr 28 | Apr 22 | Apr 18 | Apr 16 | Apr 12 | Apr 9 | Apr 7 | Apr 4 | Apr 1 |
| 20°F | Apr 15 | Apr 10 | Apr 6 | Apr 4 | Apr 3 | Apr 1 | Mar 29 | Mar 25 | Mar 19 |
| 16°F | Apr 5 | Apr 2 | Mar 30 | Mar 27 | Mar 23 | Mar 20 | Mar 18 | Mar 14 | Mar 10 |
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 | Sep 26 | Sep 30 | Oct 2 | Oct 5 | Oct 6 | Oct 9 | Oct 11 | Oct 14 | Oct 19 |
| 32°F | Oct 4 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 27 | Nov 1 |
| 28°F | Oct 14 | Oct 20 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 8 | Nov 12 |
| 24°F | Oct 28 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 12 | Nov 15 | Nov 18 | Nov 24 |
| 20°F | Nov 6 | Nov 10 | Nov 13 | Nov 16 | Nov 19 | Nov 23 | Nov 26 | Dec 1 | Dec 5 |
| 16°F | Nov 13 | Nov 19 | Nov 23 | Nov 27 | Dec 1 | Dec 3 | 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 | 164 | 157 | 152 | 148 | 144 | 140 | 137 | 133 | 127 |
| 32°F | 185 | 178 | 172 | 168 | 164 | 160 | 155 | 151 | 144 |
| 28°F | 206 | 200 | 195 | 191 | 187 | 183 | 179 | 172 | 164 |
| 24°F | 229 | 222 | 218 | 214 | 210 | 207 | 202 | 198 | 191 |
| 20°F | 252 | 246 | 241 | 236 | 231 | 228 | 223 | 219 | 212 |
| 16°F | 272 | 265 | 259 | 255 | 250 | 247 | 242 | 236 | 229 |
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
- 7,363
- Cooling degree days, base 65°F
- 297
- Growing degree days, base 40°F
- 4,023
- Growing degree days, base 45°F
- 3,009
- Growing degree days, base 50°F
- 2,128
- Growing degree days, base 55°F
- 1,369
- Growing degree days, base 60°F
- 742
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,314 | 0 | 0 |
| February | 1,177 | 0 | 0 |
| March | 1,072 | 0 | 1 |
| April | 668 | 0 | 33 |
| May | 313 | 11 | 206 |
| June | 79 | 58 | 429 |
| July | 24 | 111 | 551 |
| August | 41 | 84 | 508 |
| September | 192 | 29 | 297 |
| October | 517 | 3 | 85 |
| November | 822 | 2 | 19 |
| December | 1,142 | 0 | 0 |
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 9 km from Warsaw. 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 USC00309593 (Wyoming 3W). Public domain.