Niobrara County climate

Niobrara County Frost Dates and Growing Season

NOAA 1991-2020 normals for Lance Creek 11NNE, 17.5 km from Niobrara County, elevation 4204 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lance Creek 11NNE. 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 17 and the first fall freeze around September 25, a growing season of about 129 days.

Median at 36°F
last May 31, first September 14
Median at 32°F
last May 17, first September 25
Median at 28°F
last May 5, first October 5

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

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 31Sep 5Sep 9Sep 12Sep 14Sep 17Sep 20Sep 24Sep 28
32°FSep 9Sep 14Sep 18Sep 22Sep 25Sep 28Oct 1Oct 4Oct 8
28°FSep 20Sep 27Sep 30Oct 3Oct 5Oct 8Oct 11Oct 14Oct 19
24°FOct 1Oct 6Oct 10Oct 13Oct 16Oct 18Oct 21Oct 23Oct 27
20°FOct 10Oct 15Oct 18Oct 21Oct 23Oct 26Oct 28Oct 31Nov 5
16°FOct 17Oct 22Oct 25Oct 28Nov 1Nov 4Nov 6Nov 10Nov 15

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°F126120116111106102979285
32°F147141136133129125120115106
28°F169164159156151148144139132
24°F191184180175172168165159151
20°F212205200195191188183178170
16°F234226220214209206200193186

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
7,331
Cooling degree days, base 65°F
624
Growing degree days, base 40°F
4,377
Growing degree days, base 45°F
3,341
Growing degree days, base 50°F
2,455
Growing degree days, base 55°F
1,716
Growing degree days, base 60°F
1,108

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,26500
February1,06202
March901010
April630044
May37812175
June10285437
July9265721
August28209647
September18750336
October586276
November93307
December1,25000

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 17.5 km from Niobrara 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 USC00485374 (Lance Creek 11NNE). Public domain.