Logan County climate

Logan County Frost Dates and Growing Season

NOAA 1991-2020 normals for Sterling, 13.6 km from Logan County, elevation 3974 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sterling. 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 30 and the first fall freeze around October 9, a growing season of about 161 days.

Median at 36°F
last May 11, first October 1
Median at 32°F
last April 30, first October 9
Median at 28°F
last April 18, first October 18

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

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 18Sep 23Sep 26Sep 28Oct 1Oct 2Oct 5Oct 7Oct 11
32°FSep 28Oct 2Oct 4Oct 7Oct 9Oct 11Oct 13Oct 16Oct 20
28°FOct 6Oct 10Oct 13Oct 15Oct 18Oct 20Oct 22Oct 25Oct 29
24°FOct 15Oct 19Oct 21Oct 24Oct 26Oct 29Oct 31Nov 4Nov 8
20°FOct 21Oct 25Oct 29Nov 1Nov 4Nov 7Nov 10Nov 13Nov 18
16°FOct 26Nov 1Nov 5Nov 9Nov 12Nov 16Nov 19Nov 23Nov 27

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°F158153149145142138135131125
32°F178172168165161158154150143
28°F197192187183180176173168163
24°F221215209205202199195190183
20°F244237231227222217212206199
16°F267259254248243237231224215

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
5,938
Cooling degree days, base 65°F
1,003
Growing degree days, base 40°F
5,460
Growing degree days, base 45°F
4,281
Growing degree days, base 50°F
3,250
Growing degree days, base 55°F
2,362
Growing degree days, base 60°F
1,616

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,12100
February92201
March723029
April4672104
May20836312
June31205624
July3366827
August7289747
September99103461
October4453128
November788017
December1,12700

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 13.6 km from Logan 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 USC00057950 (Sterling). Public domain.