Elkader climate

Elkader Frost Dates and Growing Season

NOAA 1991-2020 normals for Elkader 6 Ssw, 9.6 km from Elkader, elevation 788 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Elkader 6 Ssw. 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 May 8 and the first fall freeze around October 1, a growing season of about 146 days.

Median at 36°F
last May 18, first September 23
Median at 32°F
last May 8, first October 1
Median at 28°F
last April 27, first October 11

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 31May 28May 24May 21May 18May 16May 13May 9May 4
32°FMay 22May 17May 14May 11May 8May 5May 2Apr 29Apr 24
28°FMay 13May 8May 4Apr 30Apr 27Apr 24Apr 21Apr 17Apr 13
24°FMay 3Apr 28Apr 23Apr 19Apr 16Apr 13Apr 9Apr 6Apr 2
20°FApr 22Apr 15Apr 11Apr 7Apr 4Apr 2Mar 31Mar 27Mar 21
16°FApr 9Apr 4Apr 1Mar 30Mar 27Mar 24Mar 20Mar 16Mar 12

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 11Sep 14Sep 17Sep 20Sep 23Sep 25Sep 28Oct 1Oct 4
32°FSep 18Sep 22Sep 26Sep 29Oct 1Oct 4Oct 6Oct 10Oct 14
28°FSep 26Oct 1Oct 5Oct 8Oct 11Oct 13Oct 16Oct 19Oct 24
24°FOct 6Oct 12Oct 16Oct 19Oct 21Oct 24Oct 27Oct 30Nov 2
20°FOct 18Oct 22Oct 26Oct 28Oct 31Nov 1Nov 4Nov 8Nov 13
16°FOct 27Nov 1Nov 2Nov 5Nov 9Nov 12Nov 15Nov 18Nov 25

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°F147140135130127124119114108
32°F165159154149146143138132126
28°F186179175169165161156151143
24°F208201195191188184180174166
20°F229220215211208204199194186
16°F248242236232227223218213207

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
7,512
Cooling degree days, base 65°F
582
Growing degree days, base 40°F
4,562
Growing degree days, base 45°F
3,518
Growing degree days, base 50°F
2,593
Growing degree days, base 55°F
1,790
Growing degree days, base 60°F
1,111

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,51000
February1,24500
March982115
April563471
May25933265
June47126529
July13202654
August28153590
September16756349
October5027108
November903011
December1,29401

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 9.6 km from Elkader. 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 USC00132603 (Elkader 6 Ssw). Public domain.