Hermann climate

Hermann Frost Dates and Growing Season

NOAA 1991-2020 normals for Rosebud, 28.7 km from Hermann, elevation 730 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rosebud. 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 13, a growing season of about 168 days.

Median at 36°F
last May 6, first October 2
Median at 32°F
last April 27, first October 13
Median at 28°F
last April 14, first October 24

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 21May 15May 12May 9May 6May 4May 1Apr 28Apr 23
32°FMay 12May 7May 3Apr 30Apr 27Apr 24Apr 20Apr 16Apr 11
28°FMay 5Apr 27Apr 22Apr 18Apr 14Apr 11Apr 7Apr 3Mar 28
24°FApr 21Apr 14Apr 9Apr 5Apr 3Mar 31Mar 27Mar 21Mar 14
20°FApr 7Apr 1Mar 29Mar 24Mar 21Mar 17Mar 13Mar 9Mar 3
16°FMar 27Mar 20Mar 16Mar 12Mar 9Mar 5Mar 2Feb 27Feb 21

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 18Sep 23Sep 26Sep 30Oct 2Oct 5Oct 8Oct 11Oct 16
32°FSep 29Oct 3Oct 7Oct 10Oct 13Oct 15Oct 18Oct 21Oct 26
28°FOct 9Oct 14Oct 18Oct 21Oct 24Oct 26Oct 29Nov 1Nov 5
24°FOct 19Oct 25Oct 29Nov 1Nov 3Nov 5Nov 8Nov 12Nov 18
20°FNov 1Nov 4Nov 6Nov 9Nov 13Nov 16Nov 20Nov 25Dec 1
16°FNov 7Nov 12Nov 16Nov 20Nov 24Nov 29Dec 1Dec 6Dec 11

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°F167161156152149144140135129
32°F189182177172168164159154146
28°F213206201197191187182176166
24°F236228223219215210205199190
20°F261252247242237233227222213
16°F284277270265260254250243236

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
5,353
Cooling degree days, base 65°F
1,028
Growing degree days, base 40°F
5,902
Growing degree days, base 45°F
4,649
Growing degree days, base 50°F
3,539
Growing degree days, base 55°F
2,563
Growing degree days, base 60°F
1,721

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11904
February895012
March701258
April37614171
May14666392
June20205634
July2326789
August7284742
September87111477
October34319203
November669149
December98908

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 28.7 km from Hermann. 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 USC00237300 (Rosebud). Public domain.