Marion climate

Marion Frost Dates and Growing Season

NOAA 1991-2020 normals for Princeton 1 Se, 29.9 km from Marion, elevation 497 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Princeton 1 Se. 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 11 and the first fall freeze around October 24, a growing season of about 196 days.

Median at 36°F
last April 23, first October 16
Median at 32°F
last April 11, first October 24
Median at 28°F
last March 30, first November 2

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 9May 5Apr 30Apr 27Apr 23Apr 20Apr 16Apr 12Apr 8
32°FApr 30Apr 24Apr 18Apr 14Apr 11Apr 7Apr 4Mar 31Mar 25
28°FApr 16Apr 10Apr 5Apr 1Mar 30Mar 26Mar 22Mar 18Mar 12
24°FApr 5Mar 31Mar 26Mar 22Mar 18Mar 15Mar 11Mar 5Feb 28
20°FMar 27Mar 20Mar 16Mar 12Mar 6Mar 2Feb 28Feb 22Feb 14
16°FMar 17Mar 10Mar 4Feb 28Feb 23Feb 19Feb 11Feb 4Jan 30

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 5Oct 9Oct 12Oct 14Oct 16Oct 18Oct 21Oct 23Oct 27
32°FOct 12Oct 16Oct 19Oct 21Oct 24Oct 26Oct 28Oct 31Nov 5
28°FOct 20Oct 24Oct 28Oct 31Nov 2Nov 5Nov 8Nov 11Nov 18
24°FOct 31Nov 3Nov 7Nov 10Nov 14Nov 17Nov 21Nov 26Dec 2
20°FNov 9Nov 14Nov 19Nov 23Nov 28Dec 1Dec 5Dec 11Dec 20
16°FNov 20Nov 27Dec 1Dec 6Dec 11Dec 17Dec 23Dec 28Jan 5

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°F194188183180175171166162155
32°F217210205200196191186181175
28°F243234227222217213208202195
24°F269258252247242237231225216
20°F297287278272266261254248240
16°F323314306299292286279271260

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
3,853
Cooling degree days, base 65°F
1,551
Growing degree days, base 40°F
7,326
Growing degree days, base 45°F
5,879
Growing degree days, base 50°F
4,577
Growing degree days, base 55°F
3,421
Growing degree days, base 60°F
2,412

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January877017
February685132
March4998121
April21338300
May65139540
June4308754
July0417882
August1382846
September26205629
October20449328
November4985100
December781027

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 29.9 km from Marion. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00156580 (Princeton 1 Se). Public domain.