Vandalia climate

Vandalia Frost Dates and Growing Season

NOAA 1991-2020 normals for Vandalia, 0.4 km from Vandalia, elevation 490 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Vandalia. 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 10 and the first fall freeze around October 24, a growing season of about 196 days.

Median at 36°F
last April 22, first October 14
Median at 32°F
last April 10, first October 24
Median at 28°F
last March 31, first November 3

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 6May 1Apr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 8
32°FApr 24Apr 20Apr 17Apr 13Apr 10Apr 7Apr 4Apr 1Mar 28
28°FApr 16Apr 9Apr 5Apr 2Mar 31Mar 29Mar 25Mar 19Mar 13
24°FApr 3Mar 31Mar 27Mar 23Mar 18Mar 15Mar 11Mar 7Mar 2
20°FMar 26Mar 19Mar 15Mar 12Mar 8Mar 5Mar 1Feb 25Feb 17
16°FMar 16Mar 11Mar 8Mar 4Feb 28Feb 25Feb 19Feb 14Feb 7

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 30Oct 5Oct 9Oct 11Oct 14Oct 17Oct 19Oct 21Oct 25
32°FOct 11Oct 16Oct 19Oct 21Oct 24Oct 26Oct 29Nov 1Nov 5
28°FOct 22Oct 26Oct 30Nov 1Nov 3Nov 6Nov 10Nov 14Nov 20
24°FNov 2Nov 5Nov 9Nov 12Nov 15Nov 19Nov 23Nov 27Dec 4
20°FNov 9Nov 15Nov 18Nov 23Nov 27Dec 1Dec 5Dec 10Dec 17
16°FNov 17Nov 24Nov 29Dec 3Dec 7Dec 12Dec 17Dec 22Dec 27

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°F194186181177173169165161153
32°F215209205200196193188182174
28°F241233227222218215210205199
24°F265258252246241236231227219
20°F287279273268262258252246238
16°F308299294288282278273267257

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
5,140
Cooling degree days, base 65°F
1,222
Growing degree days, base 40°F
6,248
Growing degree days, base 45°F
4,979
Growing degree days, base 50°F
3,847
Growing degree days, base 55°F
2,841
Growing degree days, base 60°F
1,963

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,12204
February89506
March686359
April34117191
May11197454
June12265703
July1363828
August2317780
September57138532
October30521228
November634156
December97508

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 0.4 km from Vandalia. 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 USC00118781 (Vandalia). Public domain.