Audrain County climate

Audrain County Frost Dates and Growing Season

NOAA 1991-2020 normals for Mexico, 5.9 km from Audrain County, elevation 802 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mexico. 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 11 and the first fall freeze around October 25, a growing season of about 197 days.

Median at 36°F
last April 23, first October 15
Median at 32°F
last April 11, first October 25
Median at 28°F
last April 1, first November 4

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 7May 3Apr 30Apr 26Apr 23Apr 20Apr 17Apr 13Apr 7
32°FApr 26Apr 21Apr 17Apr 14Apr 11Apr 7Apr 4Apr 1Mar 27
28°FApr 15Apr 10Apr 6Apr 3Apr 1Mar 29Mar 25Mar 20Mar 15
24°FApr 5Apr 1Mar 29Mar 25Mar 21Mar 18Mar 15Mar 10Mar 5
20°FMar 30Mar 23Mar 19Mar 16Mar 13Mar 9Mar 6Mar 2Feb 24
16°FMar 20Mar 15Mar 10Mar 7Mar 4Mar 2Feb 26Feb 21Feb 13

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 1Oct 7Oct 10Oct 13Oct 15Oct 18Oct 20Oct 23Oct 27
32°FOct 13Oct 18Oct 20Oct 23Oct 25Oct 27Oct 30Nov 1Nov 5
28°FOct 24Oct 28Oct 31Nov 1Nov 4Nov 6Nov 9Nov 13Nov 18
24°FNov 1Nov 5Nov 8Nov 11Nov 14Nov 17Nov 21Nov 26Dec 1
20°FNov 8Nov 13Nov 18Nov 22Nov 26Nov 30Dec 2Dec 6Dec 12
16°FNov 17Nov 24Nov 28Dec 1Dec 4Dec 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°F194188183179174170166162156
32°F216210205201197193189183176
28°F240232226222218215211206198
24°F263255248244240235230224217
20°F282274268263259254249243234
16°F302293287282277273267261253

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
5,168
Cooling degree days, base 65°F
1,275
Growing degree days, base 40°F
6,309
Growing degree days, base 45°F
5,041
Growing degree days, base 50°F
3,907
Growing degree days, base 55°F
2,902
Growing degree days, base 60°F
2,020

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,13304
February90108
March686462
April33921197
May11392447
June11261700
July0391855
August3337800
September58145538
October30023235
November631154
December99208

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 5.9 km from Audrain 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 USC00235541 (Mexico). Public domain.