Cooper County climate

Cooper County Frost Dates and Growing Season

NOAA 1991-2020 normals for Boonville, 14.7 km from Cooper County, elevation 744 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Boonville. 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 5 and the first fall freeze around October 29, a growing season of about 206 days.

Median at 36°F
last April 16, first October 19
Median at 32°F
last April 5, first October 29
Median at 28°F
last March 26, 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 10Apr 7Apr 3
32°FApr 19Apr 14Apr 10Apr 7Apr 5Apr 2Mar 31Mar 26Mar 19
28°FApr 9Apr 4Apr 1Mar 30Mar 26Mar 22Mar 18Mar 15Mar 9
24°FApr 1Mar 26Mar 21Mar 18Mar 15Mar 12Mar 8Mar 4Feb 27
20°FMar 21Mar 16Mar 12Mar 8Mar 5Mar 2Feb 28Feb 23Feb 17
16°FMar 15Mar 10Mar 6Mar 3Feb 28Feb 25Feb 20Feb 15Feb 6

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 4Oct 11Oct 14Oct 17Oct 19Oct 22Oct 24Oct 26Oct 30
32°FOct 16Oct 21Oct 24Oct 26Oct 29Nov 1Nov 3Nov 6Nov 11
28°FOct 27Nov 1Nov 2Nov 5Nov 8Nov 11Nov 14Nov 19Nov 25
24°FNov 4Nov 7Nov 12Nov 15Nov 19Nov 23Nov 27Dec 1Dec 5
20°FNov 12Nov 17Nov 22Nov 25Nov 29Dec 2Dec 6Dec 10Dec 17
16°FNov 20Nov 27Dec 1Dec 5Dec 9Dec 13Dec 17Dec 22Dec 27

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°F203196192188184180176170162
32°F227220215211206203198194187
28°F250242236232228224220214207
24°F272264258253249244239233226
20°F293285278272268263258253244
16°F310302295290286280275269260

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
4,866
Cooling degree days, base 65°F
1,497
Growing degree days, base 40°F
6,709
Growing degree days, base 45°F
5,408
Growing degree days, base 50°F
4,238
Growing degree days, base 55°F
3,197
Growing degree days, base 60°F
2,282

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,09704
February850011
March629373
April30726225
May90115492
June7313756
July0442907
August2387851
September49175577
October27132267
November607368
December956010

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 14.7 km from Cooper 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 USC00230817 (Boonville). Public domain.