Wallace County climate

Wallace County Frost Dates and Growing Season

NOAA 1991-2020 normals for Sharon Springs, 2.6 km from Wallace County, elevation 3450 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sharon Springs. 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 28 and the first fall freeze around October 15, a growing season of about 168 days.

Median at 36°F
last May 6, first October 6
Median at 32°F
last April 28, first October 15
Median at 28°F
last April 17, first October 22

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 19May 15May 11May 8May 6May 4May 2Apr 29Apr 25
32°FMay 9May 5May 2Apr 30Apr 28Apr 25Apr 22Apr 18Apr 13
28°FMay 1Apr 27Apr 23Apr 20Apr 17Apr 14Apr 11Apr 6Apr 2
24°FApr 23Apr 18Apr 13Apr 10Apr 6Apr 3Mar 31Mar 27Mar 21
20°FApr 12Apr 7Apr 3Mar 31Mar 27Mar 23Mar 19Mar 14Mar 8
16°FApr 4Mar 30Mar 25Mar 20Mar 14Mar 10Mar 6Mar 2Feb 26

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 2Oct 4Oct 6Oct 8Oct 11Oct 13Oct 17
32°FOct 3Oct 7Oct 10Oct 12Oct 15Oct 17Oct 19Oct 22Oct 25
28°FOct 9Oct 15Oct 18Oct 20Oct 22Oct 24Oct 26Oct 29Nov 1
24°FOct 18Oct 22Oct 25Oct 28Oct 30Nov 2Nov 5Nov 8Nov 12
20°FOct 25Oct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 22
16°FNov 1Nov 6Nov 10Nov 14Nov 17Nov 20Nov 23Nov 27Dec 3

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°F167162158154151148145140134
32°F186181177172168165162157151
28°F204199194190186183179174168
24°F227220214210205201196191185
20°F249242235230226222217210203
16°F271261255250246240235228220

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
5,553
Cooling degree days, base 65°F
1,166
Growing degree days, base 40°F
5,864
Growing degree days, base 45°F
4,641
Growing degree days, base 50°F
3,563
Growing degree days, base 55°F
2,629
Growing degree days, base 60°F
1,833

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07001
February90304
March709039
April4304127
May17759363
June21245674
July2394857
August4320781
September76133512
October37910179
November740026
December1,04302

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 2.6 km from Wallace County. 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 USC00147397 (Sharon Springs). Public domain.