Waseca climate

Waseca Frost Dates and Growing Season

NOAA 1991-2020 normals for Waseca S Rsch & Outreach Ctr, 1.7 km from Waseca, elevation 1153 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Waseca S Rsch & Outreach Ctr. 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 2 and the first fall freeze around October 4, a growing season of about 155 days.

Median at 36°F
last May 9, first September 26
Median at 32°F
last May 2, first October 4
Median at 28°F
last April 20, first October 14

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 22May 17May 14May 12May 9May 7May 5May 2Apr 28
32°FMay 14May 9May 6May 4May 2Apr 30Apr 26Apr 22Apr 17
28°FMay 3Apr 30Apr 26Apr 23Apr 20Apr 17Apr 14Apr 10Apr 5
24°FApr 26Apr 21Apr 17Apr 13Apr 10Apr 7Apr 5Apr 2Mar 28
20°FApr 18Apr 12Apr 8Apr 5Apr 3Mar 31Mar 27Mar 22Mar 15
16°FApr 9Apr 5Apr 2Mar 30Mar 26Mar 22Mar 18Mar 14Mar 10

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 12Sep 17Sep 21Sep 23Sep 26Sep 28Oct 1Oct 4Oct 8
32°FSep 20Sep 25Sep 28Oct 1Oct 4Oct 7Oct 10Oct 13Oct 17
28°FSep 28Oct 3Oct 7Oct 11Oct 14Oct 17Oct 20Oct 23Oct 28
24°FOct 10Oct 15Oct 19Oct 22Oct 25Oct 27Oct 30Nov 2Nov 8
20°FOct 20Oct 25Oct 28Oct 31Nov 2Nov 5Nov 8Nov 12Nov 17
16°FOct 30Nov 1Nov 4Nov 7Nov 11Nov 14Nov 17Nov 21Nov 26

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°F156150145142138135131127121
32°F175167162158155151146142136
28°F196189184180176172168162156
24°F216209204199195190186181173
20°F233226222217212208205199190
16°F253243238233229225220216207

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
8,010
Cooling degree days, base 65°F
625
Growing degree days, base 40°F
4,547
Growing degree days, base 45°F
3,539
Growing degree days, base 50°F
2,635
Growing degree days, base 55°F
1,842
Growing degree days, base 60°F
1,166

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,60400
February1,32900
March1,06409
April602367
May25941279
June46150554
July12209662
August26151590
September16464363
October5417100
November963011
December1,40100

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 1.7 km from Waseca. 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 USC00218692 (Waseca S Rsch & Outreach Ctr). Public domain.