Humboldt County climate

Humboldt County Frost Dates and Growing Season

NOAA 1991-2020 normals for Dakota City, 5.8 km from Humboldt County, elevation 1110 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dakota City. 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 26 and the first fall freeze around October 12, a growing season of about 169 days.

Median at 36°F
last May 5, first October 3
Median at 32°F
last April 26, first October 12
Median at 28°F
last April 16, first October 23

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 17May 12May 9May 7May 5May 3Apr 30Apr 27Apr 23
32°FMay 7May 5May 2Apr 29Apr 26Apr 23Apr 20Apr 16Apr 11
28°FMay 1Apr 26Apr 22Apr 18Apr 16Apr 12Apr 10Apr 6Apr 2
24°FApr 21Apr 16Apr 11Apr 9Apr 6Apr 3Mar 31Mar 28Mar 21
20°FApr 13Apr 7Apr 3Mar 31Mar 29Mar 24Mar 21Mar 16Mar 11
16°FApr 4Mar 31Mar 26Mar 22Mar 19Mar 15Mar 12Mar 8Mar 4

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 20Sep 25Sep 28Oct 1Oct 3Oct 5Oct 8Oct 11Oct 15
32°FSep 29Oct 3Oct 6Oct 9Oct 12Oct 15Oct 17Oct 20Oct 25
28°FOct 11Oct 15Oct 18Oct 20Oct 23Oct 25Oct 28Oct 31Nov 4
24°FOct 20Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 9Nov 14
20°FOct 29Nov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 18Nov 24
16°FNov 4Nov 8Nov 12Nov 15Nov 17Nov 21Nov 25Nov 29Dec 4

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°F167162157153150146142139133
32°F187181177172169165160156150
28°F207202197193190186182177171
24°F228220215211208204200194187
20°F247240235229225221217213206
16°F264257252247243238234228222

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
7,304
Cooling degree days, base 65°F
719
Growing degree days, base 40°F
4,884
Growing degree days, base 45°F
3,824
Growing degree days, base 50°F
2,871
Growing degree days, base 55°F
2,030
Growing degree days, base 60°F
1,307

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,49100
February1,23300
March974017
April544386
May22841304
June27156579
July6249708
August19188634
September12476408
October4676125
November887010
December1,30700

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 5.8 km from Humboldt 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 USC00132041 (Dakota City). Public domain.