Corydon climate

Corydon Frost Dates and Growing Season

NOAA 1991-2020 normals for Henderson 8 Ssw, 5.3 km from Corydon, elevation 449 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Henderson 8 Ssw. 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 4 and the first fall freeze around October 29, a growing season of about 207 days.

Median at 36°F
last April 16, first October 20
Median at 32°F
last April 4, first October 29
Median at 28°F
last March 26, first November 8

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 30Apr 26Apr 22Apr 19Apr 16Apr 12Apr 9Apr 6Apr 2
32°FApr 19Apr 14Apr 10Apr 7Apr 4Apr 2Mar 31Mar 27Mar 22
28°FApr 10Apr 4Apr 1Mar 29Mar 26Mar 23Mar 19Mar 14Mar 9
24°FMar 31Mar 26Mar 21Mar 17Mar 14Mar 11Mar 7Mar 2Feb 24
20°FMar 21Mar 15Mar 10Mar 6Mar 2Feb 28Feb 24Feb 19Feb 9
16°FMar 13Mar 6Mar 2Feb 26Feb 22Feb 16Feb 10Feb 4Jan 29

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 6Oct 12Oct 15Oct 18Oct 20Oct 23Oct 25Oct 27Oct 30
32°FOct 17Oct 22Oct 25Oct 27Oct 29Oct 31Nov 2Nov 5Nov 10
28°FOct 28Nov 1Nov 3Nov 5Nov 8Nov 11Nov 15Nov 21Nov 27
24°FNov 4Nov 7Nov 12Nov 15Nov 18Nov 23Nov 28Dec 2Dec 7
20°FNov 11Nov 17Nov 22Nov 27Dec 1Dec 4Dec 8Dec 14Dec 23
16°FNov 21Nov 29Dec 3Dec 7Dec 12Dec 17Dec 24Dec 30Jan 8

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°F204198194190186181178172164
32°F226220215211207203199195187
28°F252244238233227224218214207
24°F278267260254250245241235227
20°F300290283277272266261254244
16°F325315307302296289282275265

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
4,299
Cooling degree days, base 65°F
1,463
Growing degree days, base 40°F
6,970
Growing degree days, base 45°F
5,590
Growing degree days, base 50°F
4,350
Growing degree days, base 55°F
3,249
Growing degree days, base 60°F
2,287

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January966012
February765020
March574586
April25332265
May73138531
June4306751
July0395860
August1354818
September33186603
October22744304
November550381
December854018

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 5.3 km from Corydon. 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 USC00153762 (Henderson 8 Ssw). Public domain.