Clarks Grove climate

Clarks Grove Frost Dates and Growing Season

NOAA 1991-2020 normals for Albert Lea 3SE, 17.7 km from Clarks Grove, elevation 1230 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Albert Lea 3SE. 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 9, a growing season of about 164 days.

Median at 36°F
last May 7, first October 1
Median at 32°F
last April 27, first October 9
Median at 28°F
last April 15, first October 19

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 20May 15May 12May 9May 7May 5May 2Apr 30Apr 24
32°FMay 10May 6May 3Apr 30Apr 27Apr 24Apr 21Apr 17Apr 12
28°FApr 30Apr 25Apr 22Apr 19Apr 15Apr 12Apr 9Apr 6Apr 2
24°FApr 22Apr 17Apr 13Apr 9Apr 7Apr 4Apr 2Mar 30Mar 24
20°FApr 15Apr 9Apr 5Apr 2Mar 31Mar 28Mar 24Mar 20Mar 14
16°FApr 7Apr 2Mar 30Mar 26Mar 22Mar 19Mar 16Mar 13Mar 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 18Sep 23Sep 26Sep 29Oct 1Oct 4Oct 6Oct 10Oct 14
32°FSep 26Oct 1Oct 4Oct 7Oct 9Oct 12Oct 15Oct 19Oct 23
28°FOct 5Oct 10Oct 14Oct 17Oct 19Oct 22Oct 24Oct 28Nov 1
24°FOct 15Oct 21Oct 24Oct 27Oct 29Nov 1Nov 3Nov 7Nov 13
20°FOct 24Oct 30Nov 1Nov 4Nov 7Nov 10Nov 14Nov 18Nov 23
16°FNov 1Nov 5Nov 9Nov 12Nov 16Nov 19Nov 22Nov 26Dec 1

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°F164158154151147143140136130
32°F183177172168164160157152145
28°F204198193189186182177171164
24°F222215211207204199195191184
20°F241233229224221217212207200
16°F257250245241237232227223216

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
7,828
Cooling degree days, base 65°F
650
Growing degree days, base 40°F
4,617
Growing degree days, base 45°F
3,599
Growing degree days, base 50°F
2,685
Growing degree days, base 55°F
1,884
Growing degree days, base 60°F
1,202

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57500
February1,30300
March1,048010
April594366
May25237278
June42151560
July9228683
August21162606
September15263372
October5246101
November939010
December1,36900

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 17.7 km from Clarks Grove. 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 USC00210075 (Albert Lea 3SE). Public domain.