Kuna climate

Kuna Frost Dates and Growing Season

NOAA 1991-2020 normals for Boise Air Terminal, 16.7 km from Kuna, elevation 2814 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Boise Air Terminal. 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 April 24 and the first fall freeze around October 21, a growing season of about 179 days.

Median at 36°F
last May 8, first October 8
Median at 32°F
last April 24, first October 21
Median at 28°F
last April 2, first October 31

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°FMay 29May 19May 14May 10May 8May 4May 1Apr 28Apr 23
32°FMay 9May 4Apr 30Apr 27Apr 24Apr 21Apr 17Apr 12Apr 4
28°FApr 25Apr 18Apr 12Apr 6Apr 2Mar 30Mar 24Mar 18Mar 10
24°FApr 4Mar 27Mar 19Mar 13Mar 9Mar 4Mar 1Feb 24Feb 16
20°FMar 9Mar 2Feb 27Feb 23Feb 19Feb 14Feb 9Feb 2Jan 20
16°FFeb 25Feb 18Feb 13Feb 7Feb 2Jan 25Jan 15Jan 5Dec 25

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°FSep 25Sep 30Oct 3Oct 6Oct 8Oct 11Oct 14Oct 19Oct 25
32°FOct 5Oct 10Oct 14Oct 18Oct 21Oct 24Oct 27Oct 31Nov 5
28°FOct 17Oct 21Oct 25Oct 29Oct 31Nov 4Nov 8Nov 13Nov 19
24°FOct 24Oct 30Nov 4Nov 9Nov 13Nov 17Nov 21Nov 25Dec 1
20°FNov 5Nov 12Nov 17Nov 21Nov 25Nov 29Dec 3Dec 8Dec 15
16°FNov 14Nov 23Nov 27Dec 2Dec 7Dec 11Dec 16Dec 24Jan 4

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°F173166161157153148142136128
32°F203196190185179175171164156
28°F241232223217212205200194186
24°F276266260252246241234226215
20°F313302293285280274267260250
16°F346334326318311305298289277

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
98% 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
5,321
Cooling degree days, base 65°F
1,045
Growing degree days, base 40°F
5,623
Growing degree days, base 45°F
4,364
Growing degree days, base 50°F
3,290
Growing degree days, base 55°F
2,389
Growing degree days, base 60°F
1,646

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,01800
February77002
March614028
April4243101
May20042318
June61143533
July5386846
August8341798
September80119491
October37710159
November742014
December1,02001

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 16.7 km from Kuna. 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 USW00024131 (Boise Air Terminal). Public domain.