Vandalia climate

Vandalia Frost Dates and Growing Season

NOAA 1991-2020 normals for Dayton Intl AP, 2.4 km from Vandalia, elevation 1000 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dayton Intl AP. 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 16 and the first fall freeze around October 28, a growing season of about 194 days.

Median at 36°F
last April 27, first October 18
Median at 32°F
last April 16, first October 28
Median at 28°F
last April 4, first November 6

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 13May 7May 3Apr 30Apr 27Apr 24Apr 20Apr 17Apr 13
32°FMay 3Apr 27Apr 23Apr 19Apr 16Apr 14Apr 10Apr 7Apr 2
28°FApr 19Apr 14Apr 9Apr 6Apr 4Apr 1Mar 31Mar 27Mar 21
24°FApr 7Apr 3Mar 31Mar 28Mar 25Mar 22Mar 19Mar 15Mar 9
20°FMar 30Mar 26Mar 22Mar 18Mar 15Mar 12Mar 7Mar 2Feb 25
16°FMar 21Mar 16Mar 12Mar 8Mar 4Mar 1Feb 26Feb 19Feb 10

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 10Oct 13Oct 16Oct 18Oct 21Oct 23Oct 26Oct 30
32°FOct 16Oct 20Oct 24Oct 26Oct 28Oct 31Nov 1Nov 4Nov 9
28°FOct 26Oct 30Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 23
24°FNov 1Nov 6Nov 10Nov 13Nov 17Nov 20Nov 25Nov 30Dec 5
20°FNov 11Nov 16Nov 21Nov 26Nov 30Dec 3Dec 7Dec 12Dec 20
16°FNov 19Nov 27Dec 2Dec 6Dec 10Dec 15Dec 20Dec 25Dec 31

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°F191186182178173170165160153
32°F213207203199194190186182175
28°F237229223219215211207203196
24°F260252246242237233227223216
20°F284276269264259253249242232
16°F308298291285280274268262253

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
5,149
Cooling degree days, base 65°F
1,154
Growing degree days, base 40°F
6,167
Growing degree days, base 45°F
4,895
Growing degree days, base 50°F
3,757
Growing degree days, base 55°F
2,750
Growing degree days, base 60°F
1,881

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,10206
February90009
March712254
April35415182
May12594438
June13242679
July1341806
August3296758
September58139532
October30023228
November629154
December952011

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 2.4 km from Vandalia. 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 USW00093815 (Dayton Intl AP). Public domain.