Whitley County climate

Whitley County Frost Dates and Growing Season

NOAA 1991-2020 normals for Columbia City, 1.5 km from Whitley County, elevation 834 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Columbia City. 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 27 and the first fall freeze around October 17, a growing season of about 171 days.

Median at 36°F
last May 7, first October 5
Median at 32°F
last April 27, first October 17
Median at 28°F
last April 16, first October 29

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 23May 16May 13May 10May 7May 4May 1Apr 28Apr 23
32°FMay 14May 7May 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 14
28°FMay 2Apr 26Apr 22Apr 19Apr 16Apr 14Apr 11Apr 7Apr 3
24°FApr 20Apr 16Apr 12Apr 8Apr 6Apr 3Apr 1Mar 28Mar 21
20°FApr 11Apr 5Apr 2Mar 30Mar 27Mar 24Mar 20Mar 16Mar 10
16°FApr 1Mar 29Mar 24Mar 21Mar 17Mar 13Mar 10Mar 6Mar 1

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 22Sep 27Sep 30Oct 2Oct 5Oct 8Oct 11Oct 14Oct 20
32°FOct 1Oct 7Oct 11Oct 14Oct 17Oct 20Oct 23Oct 27Nov 1
28°FOct 14Oct 20Oct 23Oct 26Oct 29Nov 1Nov 2Nov 5Nov 11
24°FOct 28Nov 1Nov 3Nov 5Nov 8Nov 12Nov 15Nov 19Nov 26
20°FNov 5Nov 9Nov 14Nov 17Nov 19Nov 23Nov 28Dec 2Dec 9
16°FNov 12Nov 18Nov 22Nov 27Dec 1Dec 4Dec 8Dec 14Dec 21

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°F169163157154151146142137129
32°F193185179175171167162157149
28°F213207202198194189185180172
24°F238230224219215212207202194
20°F264255247242237233229222215
16°F285277271264258253248241234

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
6,347
Cooling degree days, base 65°F
717
Growing degree days, base 40°F
5,083
Growing degree days, base 45°F
3,944
Growing degree days, base 50°F
2,939
Growing degree days, base 55°F
2,064
Growing degree days, base 60°F
1,321

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27201
February1,06501
March872123
April498699
May20948320
June35158573
July7233691
August14183634
September11076420
October41012151
November753024
December1,10003

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 1.5 km from Whitley County. 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 USC00121739 (Columbia City). Public domain.