Box Butte County climate

Box Butte County Frost Dates and Growing Season

NOAA 1991-2020 normals for Hemingford, 11.3 km from Box Butte County, elevation 4270 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hemingford. 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 8 and the first fall freeze around October 5, a growing season of about 149 days.

Median at 36°F
last May 21, first September 27
Median at 32°F
last May 8, first October 5
Median at 28°F
last April 28, first October 15

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

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 14Sep 19Sep 22Sep 25Sep 27Sep 30Oct 2Oct 5Oct 10
32°FSep 23Sep 27Sep 30Oct 2Oct 5Oct 8Oct 11Oct 15Oct 19
28°FSep 30Oct 4Oct 8Oct 12Oct 15Oct 17Oct 20Oct 24Oct 28
24°FOct 7Oct 13Oct 16Oct 20Oct 22Oct 25Oct 28Nov 1Nov 6
20°FOct 15Oct 21Oct 25Oct 27Oct 30Nov 2Nov 6Nov 10Nov 15
16°FOct 22Oct 27Nov 1Nov 4Nov 8Nov 11Nov 15Nov 19Nov 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°F146140136132129125122117111
32°F168160156152149145141136130
28°F190184178174169166161157150
24°F210202197194190185180175168
20°F231223217212208203197192186
16°F251243236231226221214209200

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
6,800
Cooling degree days, base 65°F
658
Growing degree days, base 40°F
4,651
Growing degree days, base 45°F
3,561
Growing degree days, base 50°F
2,625
Growing degree days, base 55°F
1,835
Growing degree days, base 60°F
1,182

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,18300
February1,01901
March854017
April602158
May33115207
June80104478
July11258711
August22211654
September15568380
October5243101
November851016
December1,17001

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 11.3 km from Box Butte County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00253755 (Hemingford). Public domain.