Marion climate

Marion Frost Dates and Growing Season

NOAA 1991-2020 normals for Marion, 1.9 km from Marion, elevation 75 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 March 22 and the first fall freeze around November 11, a growing season of about 234 days.

Median at 36°F
last April 6, first November 1
Median at 32°F
last March 22, first November 11
Median at 28°F
last March 4, first November 24

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

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

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°F231223218214209205200194187
32°F263253246240234228223217208
28°F297284277271264258251244232
24°F335324314306300293285276263
20°F365356346338332326318308296
16°F365365365365365353344334323

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
99% of years
20°F or colder
86% of years
16°F or colder
49% 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
2,582
Cooling degree days, base 65°F
1,944
Growing degree days, base 40°F
8,608
Growing degree days, base 45°F
6,962
Growing degree days, base 50°F
5,460
Growing degree days, base 55°F
4,115
Growing degree days, base 60°F
2,940

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January621163
February475485
March33615199
April13858378
May23195637
June1376825
July0488953
August0442907
September7277720
October11373428
November33712176
December531490

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 1.9 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 USC00385509 (Marion). Public domain.