Lincoln Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Idaho Falls - Kifi. 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 9 and the first fall freeze around October 1, a growing season of about 142 days.
- Median at 36°F
- last May 30, first September 20
- Median at 32°F
- last May 9, first October 1
- Median at 28°F
- last April 28, first October 13
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 | Jun 16 | Jun 11 | Jun 7 | Jun 3 | May 30 | May 24 | May 19 | May 16 | May 10 |
| 32°F | Jun 2 | May 23 | May 17 | May 13 | May 9 | May 7 | May 4 | May 1 | Apr 27 |
| 28°F | May 11 | May 6 | May 3 | Apr 30 | Apr 28 | Apr 24 | Apr 21 | Apr 17 | Apr 11 |
| 24°F | Apr 29 | Apr 24 | Apr 19 | Apr 15 | Apr 11 | Apr 7 | Apr 3 | Mar 28 | Mar 20 |
| 20°F | Apr 15 | Apr 7 | Apr 2 | Mar 28 | Mar 22 | Mar 16 | Mar 11 | Mar 8 | Mar 4 |
| 16°F | Mar 27 | Mar 17 | Mar 12 | Mar 9 | Mar 6 | Mar 4 | Mar 2 | Feb 27 | Feb 20 |
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 4 | Sep 9 | Sep 14 | Sep 17 | Sep 20 | Sep 23 | Sep 25 | Sep 29 | Oct 3 |
| 32°F | Sep 17 | Sep 21 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 6 | Oct 10 | Oct 15 |
| 28°F | Sep 27 | Oct 2 | Oct 6 | Oct 9 | Oct 13 | Oct 16 | Oct 19 | Oct 23 | Oct 27 |
| 24°F | Oct 9 | Oct 14 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 3 | Nov 8 |
| 20°F | Oct 20 | Oct 25 | Oct 28 | Nov 1 | Nov 3 | Nov 5 | Nov 9 | Nov 14 | Nov 20 |
| 16°F | Oct 27 | Nov 1 | Nov 5 | Nov 9 | Nov 12 | Nov 16 | Nov 20 | Nov 23 | Nov 28 |
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 | 135 | 128 | 122 | 117 | 113 | 108 | 101 | 95 | 87 |
| 32°F | 163 | 155 | 151 | 146 | 142 | 138 | 132 | 126 | 117 |
| 28°F | 189 | 183 | 177 | 173 | 168 | 164 | 158 | 153 | 147 |
| 24°F | 218 | 211 | 206 | 202 | 197 | 191 | 186 | 180 | 173 |
| 20°F | 249 | 241 | 236 | 230 | 225 | 220 | 213 | 207 | 197 |
| 16°F | 272 | 265 | 258 | 253 | 248 | 243 | 237 | 232 | 225 |
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
- 7,144
- Cooling degree days, base 65°F
- 443
- Growing degree days, base 40°F
- 4,185
- Growing degree days, base 45°F
- 3,136
- Growing degree days, base 50°F
- 2,241
- Growing degree days, base 55°F
- 1,495
- Growing degree days, base 60°F
- 895
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,297 | 0 | 0 |
| February | 1,040 | 0 | 0 |
| March | 826 | 0 | 4 |
| April | 569 | 0 | 41 |
| May | 323 | 6 | 187 |
| June | 122 | 52 | 383 |
| July | 17 | 195 | 643 |
| August | 21 | 162 | 606 |
| September | 176 | 29 | 315 |
| October | 555 | 0 | 61 |
| November | 929 | 0 | 2 |
| December | 1,271 | 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 3.9 km from Lincoln. 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 USC00104455 (Idaho Falls - Kifi). Public domain.