Fort Hall climate

Fort Hall Frost Dates and Growing Season

NOAA 1991-2020 normals for Ft Hall 1 Nne, 2.2 km from Fort Hall, elevation 4465 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ft Hall 1 Nne. 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 20 and the first fall freeze around September 20, a growing season of about 119 days.

Median at 36°F
last June 10, first September 7
Median at 32°F
last May 20, first September 20
Median at 28°F
last May 6, first October 4

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 27Jun 21Jun 17Jun 14Jun 10Jun 7Jun 4May 31May 23
32°FJun 12Jun 4May 31May 25May 20May 17May 13May 10May 6
28°FMay 23May 15May 11May 8May 6May 3May 1Apr 27Apr 23
24°FMay 7May 3Apr 30Apr 27Apr 24Apr 20Apr 17Apr 13Apr 8
20°FApr 26Apr 21Apr 16Apr 12Apr 9Apr 5Apr 1Mar 27Mar 17
16°FApr 12Apr 3Mar 30Mar 25Mar 19Mar 14Mar 10Mar 6Mar 1

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 20Aug 29Sep 1Sep 4Sep 7Sep 11Sep 14Sep 18Sep 23
32°FSep 1Sep 7Sep 13Sep 17Sep 20Sep 24Sep 28Oct 2Oct 7
28°FSep 15Sep 22Sep 27Sep 30Oct 4Oct 7Oct 11Oct 15Oct 20
24°FSep 29Oct 5Oct 10Oct 15Oct 17Oct 21Oct 24Oct 27Nov 1
20°FOct 15Oct 20Oct 24Oct 27Oct 30Nov 1Nov 4Nov 8Nov 14
16°FOct 22Oct 27Oct 31Nov 2Nov 6Nov 10Nov 14Nov 19Nov 24

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°F11010295908681767061
32°F14213412812311911310810191
28°F170163158153149144139132122
24°F197190184179175171166160153
20°F228221214208203198194188180
16°F257249243238233226220212202

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
7,403
Cooling degree days, base 65°F
285
Growing degree days, base 40°F
3,786
Growing degree days, base 45°F
2,764
Growing degree days, base 50°F
1,917
Growing degree days, base 55°F
1,222
Growing degree days, base 60°F
672

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27700
February1,04400
March85002
April615023
May3682146
June16124318
July26134573
August35110540
September21215268
October597046
November94701
December1,27200

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 2.2 km from Fort Hall. 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 USC00103297 (Ft Hall 1 Nne). Public domain.