Marion County climate

Marion County Frost Dates and Growing Season

NOAA 1991-2020 normals for Columbia, 2.5 km from Marion County, elevation 150 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Columbia. 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 March 5 and the first fall freeze around November 19, a growing season of about 262 days.

Median at 36°F
last March 22, first November 8
Median at 32°F
last March 5, first November 19
Median at 28°F
last February 19, first December 4

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 7Apr 1Mar 29Mar 26Mar 22Mar 17Mar 12Mar 8Mar 1
32°FMar 24Mar 17Mar 13Mar 9Mar 5Mar 1Feb 26Feb 20Feb 11
28°FMar 13Mar 8Mar 1Feb 25Feb 19Feb 12Feb 5Jan 31Jan 20
24°FMar 3Feb 21Feb 9Feb 3Jan 31Jan 26Jan 19Jan 13Dec 31
20°FFeb 13Feb 3Jan 31Jan 25Jan 21Jan 16Jan 11Jan 5Dec 29
16°FFeb 2Jan 31Jan 25Jan 20Jan 14Jan 11Jan 8Jan 6Jan 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 24Oct 30Nov 2Nov 5Nov 8Nov 12Nov 15Nov 19Nov 27
32°FNov 3Nov 7Nov 12Nov 15Nov 19Nov 23Nov 29Dec 3Dec 9
28°FNov 13Nov 20Nov 26Dec 1Dec 4Dec 8Dec 18Dec 29Jan 7
24°FDec 1Dec 6Dec 13Dec 23Dec 31Jan 3Jan 7Jan 14Jan 27
20°FDec 11Dec 26Jan 1Jan 4Jan 8Jan 12Jan 17Jan 23Feb 2
16°FDec 27Jan 1Jan 5Jan 7Jan 10Jan 13Jan 19Jan 26Feb 1

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°F258249242237231226222216208
32°F293280273267262255250243235
28°F332317307299292284276269258
24°F365357344335331323314305290
20°F365365365365361351341334324
16°F365365365365365365365365348

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
99% of years
24°F or colder
88% of years
20°F or colder
54% of years
16°F or colder
18% 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
1,954
Cooling degree days, base 65°F
2,535
Growing degree days, base 40°F
9,768
Growing degree days, base 45°F
8,052
Growing degree days, base 50°F
6,453
Growing degree days, base 55°F
4,992
Growing degree days, base 60°F
3,679

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January5107109
February35513152
March21245321
April77109484
May8284741
June0453903
July0527992
August0524989
September2381829
October69152550
November27027243
December44914142

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 2.5 km from Marion 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 USC00221865 (Columbia). Public domain.