Deuel County climate

Deuel County Frost Dates and Growing Season

NOAA 1991-2020 normals for Clear Lake, 1.2 km from Deuel County, elevation 1812 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Clear Lake. 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 7 and the first fall freeze around October 1, a growing season of about 146 days.

Median at 36°F
last May 16, first September 24
Median at 32°F
last May 7, first October 1
Median at 28°F
last April 29, first October 10

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 30May 25May 22May 18May 16May 14May 11May 8May 4
32°FMay 21May 15May 12May 10May 7May 5May 2Apr 30Apr 25
28°FMay 11May 7May 4May 1Apr 29Apr 26Apr 23Apr 20Apr 15
24°FMay 3Apr 30Apr 26Apr 23Apr 20Apr 16Apr 13Apr 9Apr 5
20°FApr 26Apr 21Apr 18Apr 14Apr 11Apr 8Apr 5Apr 3Mar 29
16°FApr 19Apr 13Apr 9Apr 6Apr 3Apr 1Mar 29Mar 23Mar 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 12Sep 16Sep 19Sep 21Sep 24Sep 26Sep 28Oct 1Oct 5
32°FSep 19Sep 23Sep 26Sep 29Oct 1Oct 3Oct 6Oct 10Oct 14
28°FSep 27Oct 1Oct 4Oct 7Oct 10Oct 13Oct 16Oct 19Oct 24
24°FOct 4Oct 9Oct 13Oct 16Oct 20Oct 23Oct 25Oct 29Nov 1
20°FOct 14Oct 20Oct 23Oct 26Oct 29Nov 1Nov 3Nov 7Nov 12
16°FOct 23Oct 29Nov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19

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°F146140136132129126121116111
32°F163157153150146142139135129
28°F183176172168164161156151144
24°F203196191187183178173169161
20°F220213209206201196191186177
16°F238230226221217213209203197

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
8,664
Cooling degree days, base 65°F
458
Growing degree days, base 40°F
4,084
Growing degree days, base 45°F
3,124
Growing degree days, base 50°F
2,274
Growing degree days, base 55°F
1,539
Growing degree days, base 60°F
927

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,65500
February1,37100
March1,15005
April692141
May32920213
June8089460
July19177623
August40127552
September20742305
October612370
November1,03505
December1,47400

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 1.2 km from Deuel 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 USC00391777 (Clear Lake). Public domain.