Marion climate

Marion Frost Dates and Growing Season

NOAA 1991-2020 normals for Clintonville, 12.4 km from Marion, elevation 802 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Clintonville. 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 4 and the first fall freeze around October 6, a growing season of about 154 days.

Median at 36°F
last May 15, first September 28
Median at 32°F
last May 4, first October 6
Median at 28°F
last April 24, first October 18

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 19May 15May 13May 10May 7May 2
32°FMay 19May 14May 10May 7May 4May 2Apr 30Apr 26Apr 22
28°FMay 7May 3Apr 30Apr 27Apr 24Apr 22Apr 19Apr 15Apr 10
24°FApr 27Apr 22Apr 19Apr 15Apr 12Apr 9Apr 7Apr 4Mar 31
20°FApr 17Apr 12Apr 8Apr 5Apr 3Apr 1Mar 30Mar 26Mar 19
16°FApr 8Apr 4Apr 1Mar 30Mar 27Mar 23Mar 20Mar 16Mar 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°FSep 14Sep 18Sep 22Sep 24Sep 28Sep 30Oct 2Oct 5Oct 9
32°FSep 21Sep 27Oct 1Oct 3Oct 6Oct 9Oct 11Oct 15Oct 19
28°FOct 1Oct 7Oct 11Oct 14Oct 18Oct 21Oct 24Oct 28Nov 1
24°FOct 14Oct 21Oct 25Oct 28Oct 31Nov 2Nov 5Nov 9Nov 14
20°FOct 27Nov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 20Nov 25
16°FNov 4Nov 9Nov 13Nov 16Nov 18Nov 21Nov 24Nov 28Dec 2

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°F152146140136133129125121115
32°F173166161157154149146140134
28°F195189183179175171166161154
24°F219213208203199195191186179
20°F239233228224220216212208201
16°F257250245241237233229225217

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
7,906
Cooling degree days, base 65°F
467
Growing degree days, base 40°F
4,189
Growing degree days, base 45°F
3,198
Growing degree days, base 50°F
2,328
Growing degree days, base 55°F
1,577
Growing degree days, base 60°F
949

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,51300
February1,27700
March1,07106
April649141
May30023225
June7099479
July16179628
August32126559
September18937312
October550373
November92305
December1,31700

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 12.4 km from Marion. 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 USC00471676 (Clintonville). Public domain.