Broken Bow climate

Broken Bow Frost Dates and Growing Season

NOAA 1991-2020 normals for Broken Bow 1 N, 2.3 km from Broken Bow, elevation 475 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Broken Bow 1 N. 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 1 and the first fall freeze around November 2, a growing season of about 220 days.

Median at 36°F
last April 13, first October 25
Median at 32°F
last April 1, first November 2
Median at 28°F
last March 13, first November 14

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°FApr 28Apr 23Apr 20Apr 17Apr 13Apr 10Apr 6Apr 2Mar 28
32°FApr 17Apr 11Apr 7Apr 4Apr 1Mar 28Mar 23Mar 18Mar 10
28°FApr 3Mar 28Mar 21Mar 17Mar 13Mar 9Mar 5Mar 1Feb 24
24°FMar 18Mar 12Mar 7Mar 4Mar 1Feb 25Feb 21Feb 16Feb 9
20°FMar 8Mar 2Feb 24Feb 18Feb 14Feb 8Feb 3Jan 28Jan 19
16°FFeb 28Feb 13Feb 6Feb 1Jan 29Jan 23Jan 17Jan 10Jan 1

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°FOct 12Oct 16Oct 19Oct 22Oct 25Oct 27Oct 30Nov 1Nov 7
32°FOct 20Oct 26Oct 29Nov 1Nov 2Nov 5Nov 9Nov 13Nov 19
28°FOct 31Nov 3Nov 6Nov 10Nov 14Nov 18Nov 22Nov 28Dec 4
24°FNov 8Nov 14Nov 20Nov 25Nov 28Dec 1Dec 6Dec 11Dec 21
20°FNov 22Nov 29Dec 3Dec 9Dec 16Dec 22Dec 28Jan 2Jan 10
16°FDec 5Dec 12Dec 21Dec 26Jan 1Jan 4Jan 9Jan 16Jan 26

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°F217209203199195190186181175
32°F244235229224220215210205196
28°F271263257251246241236229220
24°F301293284278273268262256248
20°F335325316309303297292284274
16°F365353345338334328321312302

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
99% of years
16°F or colder
87% 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
3,079
Cooling degree days, base 65°F
1,927
Growing degree days, base 40°F
8,194
Growing degree days, base 45°F
6,626
Growing degree days, base 50°F
5,211
Growing degree days, base 55°F
3,960
Growing degree days, base 60°F
2,865

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January749019
February561152
March36810176
April16043343
May34165597
June0354804
July0495959
August0487951
September8289730
October14376405
November3977137
December660140

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 2.3 km from Broken Bow. 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 USC00341162 (Broken Bow 1 N). Public domain.