Wathena climate

Wathena Frost Dates and Growing Season

NOAA 1991-2020 normals for St Joseph Rosecrans AP, 2.8 km from Wathena, elevation 818 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for St Joseph Rosecrans AP. 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 19 and the first fall freeze around October 17, a growing season of about 180 days.

Median at 36°F
last April 29, first October 5
Median at 32°F
last April 19, first October 17
Median at 28°F
last April 9, first October 26

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 9May 5May 3May 1Apr 29Apr 26Apr 23Apr 20Apr 15
32°FMay 3Apr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 10Apr 5
28°FApr 24Apr 18Apr 15Apr 12Apr 9Apr 6Apr 3Mar 31Mar 25
24°FApr 14Apr 9Apr 5Apr 2Mar 30Mar 26Mar 22Mar 18Mar 11
20°FApr 4Mar 31Mar 26Mar 23Mar 19Mar 16Mar 12Mar 6Mar 1
16°FMar 26Mar 20Mar 16Mar 12Mar 9Mar 5Mar 2Feb 26Feb 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 21Sep 26Sep 30Oct 2Oct 5Oct 8Oct 11Oct 15Oct 20
32°FSep 30Oct 6Oct 10Oct 13Oct 17Oct 19Oct 22Oct 26Oct 30
28°FOct 13Oct 18Oct 21Oct 24Oct 26Oct 29Nov 1Nov 4Nov 8
24°FOct 23Oct 28Oct 31Nov 2Nov 5Nov 7Nov 11Nov 14Nov 20
20°FNov 1Nov 4Nov 7Nov 11Nov 14Nov 17Nov 22Nov 26Dec 2
16°FNov 7Nov 13Nov 17Nov 21Nov 25Nov 29Dec 2Dec 6Dec 12

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°F179173168164160156151147139
32°F201194189184180176172166159
28°F221214208204200195191186180
24°F242234228224219215211205198
20°F266258252246241236231225218
16°F283275269265260256251244237

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
5,385
Cooling degree days, base 65°F
1,288
Growing degree days, base 40°F
6,221
Growing degree days, base 45°F
4,975
Growing degree days, base 50°F
3,861
Growing degree days, base 55°F
2,874
Growing degree days, base 60°F
2,016

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,17001
February92407
March676360
April35218185
May113105461
June7284727
July1394859
August3324786
September71133513
October32625221
November691139
December1,05103

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 2.8 km from Wathena. 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 USW00013993 (St Joseph Rosecrans AP). Public domain.