Sheridan County climate

Sheridan County Frost Dates and Growing Season

NOAA 1991-2020 normals for Sheridan Fld Stn, 6.5 km from Sheridan County, elevation 3750 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sheridan Fld Stn. 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 18 and the first fall freeze around September 24, a growing season of about 127 days.

Median at 36°F
last May 31, first September 12
Median at 32°F
last May 18, first September 24
Median at 28°F
last May 5, first October 3

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

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 29Sep 3Sep 7Sep 10Sep 12Sep 15Sep 18Sep 22Sep 27
32°FSep 9Sep 15Sep 18Sep 21Sep 24Sep 26Sep 29Oct 2Oct 7
28°FSep 20Sep 25Sep 28Oct 1Oct 3Oct 6Oct 9Oct 14Oct 18
24°FSep 29Oct 3Oct 7Oct 12Oct 15Oct 18Oct 20Oct 23Oct 27
20°FOct 5Oct 12Oct 17Oct 20Oct 24Oct 26Oct 29Nov 2Nov 6
16°FOct 15Oct 21Oct 25Oct 28Oct 31Nov 3Nov 6Nov 11Nov 16

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°F12211511010610398948982
32°F147141136131127123119113107
28°F171164158153149146142136129
24°F192185180175171167162157150
20°F215207202197192186181175167
16°F238229222216211206199193183

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
7,780
Cooling degree days, base 65°F
473
Growing degree days, base 40°F
4,003
Growing degree days, base 45°F
3,003
Growing degree days, base 50°F
2,157
Growing degree days, base 55°F
1,460
Growing degree days, base 60°F
897

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33600
February1,13001
March93606
April655136
May3926150
June13455377
July22211654
August41167591
September22633284
October624155
November98304
December1,30200

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 6.5 km from Sheridan 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 USC00488160 (Sheridan Fld Stn). Public domain.