Chubbuck Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Pocatello City. 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 2 and the first fall freeze around October 11, a growing season of about 161 days.
- Median at 36°F
- last May 17, first September 30
- Median at 32°F
- last May 2, first October 11
- Median at 28°F
- last April 17, first October 24
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 5 | May 29 | May 24 | May 21 | May 17 | May 14 | May 10 | May 7 | May 1 |
| 32°F | May 18 | May 13 | May 9 | May 5 | May 2 | Apr 29 | Apr 27 | Apr 23 | Apr 17 |
| 28°F | May 4 | Apr 28 | Apr 24 | Apr 20 | Apr 17 | Apr 13 | Apr 10 | Apr 5 | Mar 30 |
| 24°F | Apr 17 | Apr 10 | Apr 6 | Apr 1 | Mar 30 | Mar 26 | Mar 21 | Mar 15 | Mar 9 |
| 20°F | Mar 30 | Mar 23 | Mar 18 | Mar 13 | Mar 10 | Mar 7 | Mar 4 | Mar 1 | Feb 24 |
| 16°F | Mar 13 | Mar 9 | Mar 6 | Mar 3 | Mar 1 | Feb 27 | Feb 23 | Feb 18 | 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 | Sep 12 | Sep 19 | Sep 24 | Sep 27 | Sep 30 | Oct 2 | Oct 5 | Oct 9 | Oct 15 |
| 32°F | Sep 26 | Oct 2 | Oct 5 | Oct 9 | Oct 11 | Oct 15 | Oct 18 | Oct 21 | Oct 26 |
| 28°F | Oct 8 | Oct 14 | Oct 18 | Oct 20 | Oct 24 | Oct 26 | Oct 30 | Nov 2 | Nov 6 |
| 24°F | Oct 19 | Oct 25 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 13 | Nov 18 |
| 20°F | Oct 27 | Nov 1 | Nov 6 | Nov 10 | Nov 14 | Nov 16 | Nov 19 | Nov 22 | Nov 26 |
| 16°F | Nov 3 | Nov 10 | Nov 15 | Nov 19 | Nov 22 | Nov 25 | Nov 28 | Dec 1 | Dec 7 |
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 | 156 | 148 | 144 | 138 | 134 | 129 | 125 | 118 | 110 |
| 32°F | 180 | 174 | 169 | 165 | 161 | 157 | 152 | 148 | 139 |
| 28°F | 211 | 203 | 197 | 192 | 188 | 183 | 179 | 172 | 165 |
| 24°F | 240 | 232 | 227 | 221 | 216 | 212 | 207 | 202 | 192 |
| 20°F | 266 | 258 | 254 | 249 | 244 | 239 | 235 | 229 | 220 |
| 16°F | 288 | 280 | 275 | 270 | 266 | 262 | 257 | 252 | 243 |
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
- 6,130
- Cooling degree days, base 65°F
- 755
- Growing degree days, base 40°F
- 4,971
- Growing degree days, base 45°F
- 3,823
- Growing degree days, base 50°F
- 2,830
- Growing degree days, base 55°F
- 1,994
- Growing degree days, base 60°F
- 1,307
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,128 | 0 | 0 |
| February | 942 | 0 | 0 |
| March | 729 | 0 | 16 |
| April | 488 | 1 | 71 |
| May | 253 | 17 | 248 |
| June | 80 | 108 | 480 |
| July | 4 | 308 | 770 |
| August | 10 | 250 | 705 |
| September | 111 | 68 | 413 |
| October | 443 | 3 | 120 |
| November | 813 | 0 | 8 |
| December | 1,129 | 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 5.3 km from Chubbuck. 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 USC00107210 (Pocatello City). Public domain.