Arbon Valley climate

Arbon Valley Frost Dates and Growing Season

NOAA 1991-2020 normals for Pocatello Rgnl AP, 4.3 km from Arbon Valley, elevation 4478 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pocatello Rgnl AP. 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 23 and the first fall freeze around September 18, a growing season of about 117 days.

Median at 36°F
last June 11, first September 7
Median at 32°F
last May 23, first September 18
Median at 28°F
last May 6, first October 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.

Threshold10%20%30%40%50%60%70%80%90%
36°FJun 28Jun 22Jun 18Jun 15Jun 11Jun 8Jun 5May 31May 23
32°FJun 13Jun 7Jun 2May 28May 23May 18May 15May 11May 6
28°FMay 23May 17May 12May 9May 6May 3Apr 30Apr 27Apr 21
24°FMay 9May 5May 1Apr 27Apr 22Apr 17Apr 13Apr 9Apr 2
20°FApr 23Apr 15Apr 10Apr 4Mar 31Mar 27Mar 19Mar 12Mar 7
16°FApr 3Mar 27Mar 17Mar 11Mar 8Mar 5Mar 2Feb 26Feb 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.

Threshold10%20%30%40%50%60%70%80%90%
36°FAug 25Aug 30Sep 1Sep 4Sep 7Sep 10Sep 12Sep 16Sep 21
32°FSep 3Sep 8Sep 12Sep 15Sep 18Sep 21Sep 25Sep 29Oct 4
28°FSep 14Sep 20Sep 25Sep 28Oct 1Oct 5Oct 8Oct 12Oct 16
24°FSep 27Oct 3Oct 7Oct 11Oct 15Oct 18Oct 21Oct 25Nov 1
20°FOct 8Oct 15Oct 20Oct 24Oct 27Oct 30Nov 2Nov 6Nov 13
16°FOct 20Oct 27Oct 30Nov 2Nov 6Nov 11Nov 15Nov 20Nov 26

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.

Threshold10%20%30%40%50%60%70%80%90%
36°F10710195918682787265
32°F1421341281231171121079991
28°F169162156152147143137131124
24°F202193187181176171165159150
20°F239230222216211205199192181
16°F267258251246240235229221211

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
6,954
Cooling degree days, base 65°F
431
Growing degree days, base 40°F
4,154
Growing degree days, base 45°F
3,088
Growing degree days, base 50°F
2,194
Growing degree days, base 55°F
1,461
Growing degree days, base 60°F
874

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22000
February99000
March80205
April579033
May3405171
June12946371
July16195645
August25158598
September18627304
October554064
November90204
December1,21500

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 4.3 km from Arbon Valley. 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 USW00024156 (Pocatello Rgnl AP). Public domain.