Humboldt climate

Humboldt Frost Dates and Growing Season

NOAA 1991-2020 normals for Jackson 4 Ne, 14.8 km from Humboldt, elevation 430 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Jackson 4 Ne. 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 4 and the first fall freeze around October 30, a growing season of about 208 days.

Median at 36°F
last April 16, first October 22
Median at 32°F
last April 4, first October 30
Median at 28°F
last March 24, first November 8

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 1Apr 27Apr 23Apr 20Apr 16Apr 13Apr 9Apr 5Mar 31
32°FApr 21Apr 16Apr 11Apr 7Apr 4Apr 2Mar 30Mar 24Mar 18
28°FApr 11Apr 5Apr 2Mar 29Mar 24Mar 20Mar 16Mar 11Mar 4
24°FApr 2Mar 26Mar 19Mar 15Mar 11Mar 6Mar 2Feb 26Feb 19
20°FMar 21Mar 13Mar 7Mar 2Feb 28Feb 24Feb 19Feb 12Feb 3
16°FMar 9Mar 1Feb 25Feb 19Feb 12Feb 6Jan 31Jan 25Jan 12

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 10Oct 14Oct 17Oct 20Oct 22Oct 24Oct 26Oct 29Nov 3
32°FOct 18Oct 22Oct 25Oct 28Oct 30Nov 1Nov 4Nov 8Nov 13
28°FOct 27Oct 31Nov 3Nov 5Nov 8Nov 11Nov 15Nov 21Nov 28
24°FNov 5Nov 9Nov 13Nov 17Nov 21Nov 25Nov 29Dec 2Dec 9
20°FNov 14Nov 20Nov 26Dec 1Dec 3Dec 7Dec 12Dec 18Dec 28
16°FNov 30Dec 4Dec 10Dec 16Dec 23Dec 28Jan 2Jan 9Jan 20

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°F208201196193189184180175169
32°F230222217213208205200195188
28°F254244238233229225219213207
24°F281270265259254249243236228
20°F311301292286280274268261252
16°F344333326318311306299291279

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
97% 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
3,763
Cooling degree days, base 65°F
1,715
Growing degree days, base 40°F
7,548
Growing degree days, base 45°F
6,089
Growing degree days, base 50°F
4,765
Growing degree days, base 55°F
3,598
Growing degree days, base 60°F
2,587

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January843026
February668140
March48610124
April22046303
May58161568
June1338787
July0457922
August0420885
September23222649
October20355332
November498596
December761132

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 14.8 km from Humboldt. 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 USC00404568 (Jackson 4 Ne). Public domain.