Marion climate

Marion Frost Dates and Growing Season

NOAA 1991-2020 normals for Marion, 0.1 km from Marion, elevation 1410 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Marion. 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 November 1, a growing season of about 209 days.

Median at 36°F
last April 19, first October 22
Median at 32°F
last April 5, first November 1
Median at 28°F
last March 24, first November 11

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 6May 1Apr 25Apr 22Apr 19Apr 15Apr 11Apr 7Apr 3
32°FApr 21Apr 16Apr 11Apr 8Apr 5Apr 2Mar 31Mar 27Mar 20
28°FApr 8Apr 3Mar 31Mar 28Mar 24Mar 20Mar 16Mar 12Mar 2
24°FMar 31Mar 25Mar 20Mar 16Mar 13Mar 7Mar 2Feb 25Feb 12
20°FMar 20Mar 13Mar 8Mar 1Feb 25Feb 18Feb 10Feb 3Jan 28
16°FMar 11Feb 28Feb 20Feb 10Feb 3Jan 30Jan 24Jan 15Jan 5

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 25Oct 28Oct 31Nov 4
32°FOct 18Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 9Nov 15
28°FOct 29Nov 2Nov 4Nov 8Nov 11Nov 15Nov 18Nov 25Dec 1
24°FNov 7Nov 12Nov 17Nov 23Nov 27Dec 1Dec 4Dec 9Dec 22
20°FNov 18Nov 27Dec 1Dec 5Dec 10Dec 15Dec 23Dec 31Jan 8
16°FDec 2Dec 7Dec 13Dec 20Dec 25Dec 31Jan 5Jan 12Jan 22

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°F207200194190186181177172165
32°F231223218214209205201195189
28°F259250243238233228223218210
24°F291281274267261255249243235
20°F324312305298291284278269258
16°F353340334327319311304295282

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
94% 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
3,761
Cooling degree days, base 65°F
1,203
Growing degree days, base 40°F
6,895
Growing degree days, base 45°F
5,415
Growing degree days, base 50°F
4,104
Growing degree days, base 55°F
2,968
Growing degree days, base 60°F
2,004

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January818012
February643020
March501495
April23622258
May7993480
June10241681
July1342806
August1310773
September30165585
October22125287
November483285
December738022

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 0.1 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 USC00315340 (Marion). Public domain.