Elgin Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Theilman 1SSW. 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 7 and the first fall freeze around October 2, a growing season of about 148 days.
- Median at 36°F
- last May 16, first September 26
- Median at 32°F
- last May 7, first October 2
- Median at 28°F
- last April 28, first October 12
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 30 | May 25 | May 22 | May 19 | May 16 | May 14 | May 11 | May 8 | May 4 |
| 32°F | May 22 | May 15 | May 12 | May 9 | May 7 | May 4 | May 2 | Apr 29 | Apr 24 |
| 28°F | May 12 | May 7 | May 3 | May 1 | Apr 28 | Apr 26 | Apr 23 | Apr 19 | Apr 13 |
| 24°F | May 3 | Apr 29 | Apr 24 | Apr 21 | Apr 18 | Apr 13 | Apr 9 | Apr 5 | Apr 1 |
| 20°F | Apr 26 | Apr 19 | Apr 13 | Apr 9 | Apr 6 | Apr 3 | Apr 1 | Mar 29 | Mar 23 |
| 16°F | Apr 13 | Apr 6 | Apr 4 | Apr 1 | Mar 30 | Mar 27 | Mar 23 | Mar 19 | Mar 14 |
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 12 | Sep 17 | Sep 20 | Sep 23 | Sep 26 | Sep 28 | Oct 1 | Oct 3 | Oct 6 |
| 32°F | Sep 20 | Sep 24 | Sep 27 | Sep 30 | Oct 2 | Oct 4 | Oct 7 | Oct 10 | Oct 15 |
| 28°F | Sep 27 | Oct 1 | Oct 5 | Oct 8 | Oct 12 | Oct 15 | Oct 18 | Oct 21 | Oct 25 |
| 24°F | Oct 6 | Oct 12 | Oct 16 | Oct 20 | Oct 23 | Oct 25 | Oct 29 | Nov 1 | Nov 5 |
| 20°F | Oct 19 | Oct 26 | Oct 29 | Nov 1 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 18 |
| 16°F | Oct 31 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 16 | Nov 20 | Nov 23 | Nov 27 |
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 | 147 | 142 | 138 | 134 | 131 | 127 | 123 | 118 | 111 |
| 32°F | 166 | 160 | 156 | 152 | 148 | 144 | 140 | 135 | 128 |
| 28°F | 187 | 180 | 175 | 171 | 167 | 162 | 157 | 153 | 146 |
| 24°F | 208 | 201 | 197 | 192 | 189 | 183 | 178 | 172 | 164 |
| 20°F | 230 | 224 | 218 | 214 | 209 | 205 | 200 | 194 | 184 |
| 16°F | 249 | 241 | 236 | 232 | 227 | 223 | 219 | 214 | 207 |
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
- 7,860
- Cooling degree days, base 65°F
- 614
- Growing degree days, base 40°F
- 4,493
- Growing degree days, base 45°F
- 3,482
- Growing degree days, base 50°F
- 2,582
- Growing degree days, base 55°F
- 1,803
- Growing degree days, base 60°F
- 1,143
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,572 | 0 | 0 |
| February | 1,298 | 0 | 0 |
| March | 1,042 | 1 | 10 |
| April | 601 | 2 | 59 |
| May | 275 | 32 | 254 |
| June | 52 | 135 | 533 |
| July | 11 | 219 | 673 |
| August | 23 | 163 | 604 |
| September | 168 | 59 | 353 |
| October | 535 | 5 | 91 |
| November | 932 | 0 | 7 |
| December | 1,352 | 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 17.4 km from Elgin. 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 USC00218227 (Theilman 1SSW). Public domain.