Ossian climate

Ossian Frost Dates and Growing Season

NOAA 1991-2020 normals for Bluffton 6N, 7.5 km from Ossian, elevation 861 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bluffton 6N. 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 24 and the first fall freeze around October 20, a growing season of about 179 days.

Median at 36°F
last May 3, first October 10
Median at 32°F
last April 24, first October 20
Median at 28°F
last April 12, first November 1

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 18May 13May 9May 6May 3May 1Apr 29Apr 25Apr 20
32°FMay 9May 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 16Apr 10
28°FApr 27Apr 21Apr 18Apr 15Apr 12Apr 8Apr 5Apr 3Mar 30
24°FApr 15Apr 9Apr 6Apr 3Apr 1Mar 30Mar 26Mar 22Mar 16
20°FApr 4Mar 31Mar 29Mar 25Mar 22Mar 18Mar 15Mar 11Mar 6
16°FMar 29Mar 22Mar 18Mar 15Mar 11Mar 8Mar 5Mar 1Feb 23

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 27Oct 1Oct 4Oct 7Oct 10Oct 13Oct 15Oct 18Oct 22
32°FOct 6Oct 11Oct 15Oct 17Oct 20Oct 23Oct 26Oct 30Nov 3
28°FOct 19Oct 23Oct 26Oct 29Nov 1Nov 2Nov 6Nov 9Nov 15
24°FNov 1Nov 3Nov 6Nov 9Nov 13Nov 17Nov 21Nov 26Dec 1
20°FNov 8Nov 13Nov 16Nov 21Nov 25Nov 29Dec 2Dec 6Dec 12
16°FNov 15Nov 22Nov 27Nov 30Dec 3Dec 7Dec 11Dec 17Dec 23

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°F176170165161157154149145138
32°F198192187183179175171165158
28°F222214210206202198193188181
24°F248240234230225221217212205
20°F271262256251246242238232224
16°F293284278272267261255250242

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
6,184
Cooling degree days, base 65°F
798
Growing degree days, base 40°F
5,270
Growing degree days, base 45°F
4,115
Growing degree days, base 50°F
3,091
Growing degree days, base 55°F
2,194
Growing degree days, base 60°F
1,430

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,25402
February1,05302
March860124
April4798111
May18859349
June31181600
July5251711
August12199652
September9888443
October39012164
November734029
December1,08204

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 7.5 km from Ossian. 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 USC00120830 (Bluffton 6N). Public domain.