Bowman County climate

Bowman County Frost Dates and Growing Season

NOAA 1991-2020 normals for Bowman, 14.6 km from Bowman County, elevation 2983 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bowman. 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 16 and the first fall freeze around September 25, a growing season of about 132 days.

Median at 36°F
last May 27, first September 17
Median at 32°F
last May 16, first September 25
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 10Jun 4Jun 1May 29May 27May 24May 22May 18May 16
32°FMay 29May 24May 21May 18May 16May 14May 11May 9May 5
28°FMay 17May 12May 9May 7May 5May 3May 1Apr 29Apr 22
24°FMay 7May 3Apr 30Apr 28Apr 25Apr 22Apr 19Apr 16Apr 12
20°FApr 29Apr 25Apr 21Apr 18Apr 15Apr 12Apr 9Apr 6Apr 2
16°FApr 21Apr 16Apr 12Apr 9Apr 6Apr 4Mar 31Mar 26Mar 18

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 2Sep 7Sep 11Sep 14Sep 17Sep 19Sep 22Sep 25Sep 29
32°FSep 11Sep 17Sep 20Sep 23Sep 25Sep 28Sep 30Oct 3Oct 7
28°FSep 20Sep 25Sep 28Sep 30Oct 3Oct 6Oct 9Oct 12Oct 16
24°FSep 27Oct 2Oct 6Oct 10Oct 13Oct 15Oct 18Oct 21Oct 25
20°FOct 6Oct 11Oct 15Oct 18Oct 21Oct 24Oct 27Oct 30Nov 3
16°FOct 15Oct 20Oct 24Oct 27Oct 29Nov 1Nov 4Nov 8Nov 14

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°F12812211711411110810510093
32°F148142139135132128124119113
28°F167161156153150146142138131
24°F187180176172168164160155149
20°F207201195191187183178173166
16°F228221215210205201197191183

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
8,638
Cooling degree days, base 65°F
396
Growing degree days, base 40°F
3,754
Growing degree days, base 45°F
2,819
Growing degree days, base 50°F
2,016
Growing degree days, base 55°F
1,342
Growing degree days, base 60°F
800

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,50700
February1,27800
March1,09903
April729025
May4116146
June13447368
July35166597
August51143558
September25132267
October682248
November1,05904
December1,40300

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 14.6 km from Bowman 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 USC00320995 (Bowman). Public domain.