Clever climate

Clever Frost Dates and Growing Season

NOAA 1991-2020 normals for Billings 1SW, 9.5 km from Clever, elevation 1310 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Billings 1SW. 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 15 and the first fall freeze around October 23, a growing season of about 189 days.

Median at 36°F
last April 28, first October 14
Median at 32°F
last April 15, first October 23
Median at 28°F
last April 4, first November 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°FMay 11May 6May 3Apr 30Apr 28Apr 24Apr 20Apr 16Apr 10
32°FMay 2Apr 27Apr 22Apr 18Apr 15Apr 11Apr 8Apr 4Mar 30
28°FApr 19Apr 13Apr 10Apr 7Apr 4Mar 31Mar 29Mar 24Mar 18
24°FApr 10Apr 5Mar 31Mar 29Mar 24Mar 21Mar 17Mar 12Mar 6
20°FMar 31Mar 24Mar 19Mar 16Mar 13Mar 9Mar 6Mar 2Feb 23
16°FMar 19Mar 14Mar 10Mar 6Mar 3Feb 28Feb 24Feb 18Feb 9

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°FOct 1Oct 5Oct 8Oct 11Oct 14Oct 16Oct 18Oct 22Oct 26
32°FOct 11Oct 15Oct 18Oct 21Oct 23Oct 25Oct 28Oct 31Nov 4
28°FOct 20Oct 24Oct 27Oct 30Nov 1Nov 4Nov 7Nov 11Nov 16
24°FOct 27Nov 1Nov 4Nov 7Nov 10Nov 13Nov 17Nov 22Nov 28
20°FNov 4Nov 9Nov 14Nov 18Nov 21Nov 26Nov 30Dec 2Dec 8
16°FNov 12Nov 19Nov 23Nov 28Dec 1Dec 5Dec 10Dec 17Dec 23

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°F188181177172169165162157150
32°F211203198193189185181177170
28°F231224219215211207203197190
24°F255247241235231226221216210
20°F277269264259254248242237228
16°F301292285280275269265258248

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
4,505
Cooling degree days, base 65°F
1,385
Growing degree days, base 40°F
6,741
Growing degree days, base 45°F
5,380
Growing degree days, base 50°F
4,165
Growing degree days, base 55°F
3,095
Growing degree days, base 60°F
2,167

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January98409
February767020
March586384
April30020222
May9998466
June7268711
July1407871
August2377840
September40176587
October26433270
November575269
December880015

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 9.5 km from Clever. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00230657 (Billings 1SW). Public domain.