Springport climate

Springport Frost Dates and Growing Season

NOAA 1991-2020 normals for Eaton Rapids, 16 km from Springport, elevation 870 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Eaton Rapids. 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 30 and the first fall freeze around October 14, a growing season of about 165 days.

Median at 36°F
last May 10, first October 2
Median at 32°F
last April 30, first October 14
Median at 28°F
last April 19, first October 27

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 25May 21May 17May 14May 10May 7May 4Apr 30Apr 26
32°FMay 16May 11May 6May 3Apr 30Apr 27Apr 24Apr 21Apr 16
28°FMay 6Apr 30Apr 25Apr 22Apr 19Apr 16Apr 13Apr 9Apr 5
24°FApr 20Apr 16Apr 12Apr 9Apr 6Apr 4Apr 2Mar 31Mar 24
20°FApr 9Apr 5Apr 2Mar 31Mar 30Mar 26Mar 22Mar 19Mar 14
16°FApr 1Mar 30Mar 27Mar 23Mar 20Mar 17Mar 14Mar 11Mar 4

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 25Sep 28Sep 30Oct 2Oct 5Oct 7Oct 10Oct 15
32°FOct 1Oct 5Oct 8Oct 11Oct 14Oct 17Oct 20Oct 23Oct 29
28°FOct 12Oct 17Oct 21Oct 24Oct 27Oct 30Nov 1Nov 5Nov 10
24°FOct 25Oct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 24
20°FNov 6Nov 10Nov 14Nov 18Nov 22Nov 25Nov 29Dec 2Dec 8
16°FNov 17Nov 23Nov 28Dec 1Dec 4Dec 7Dec 11Dec 17Dec 22

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°F163157152148145141137132125
32°F186179174170165161157152146
28°F210203199194191186182176169
24°F237228223219215211207202194
20°F261254249243239234230225218
16°F281273268263258253248243236

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
6,736
Cooling degree days, base 65°F
606
Growing degree days, base 40°F
4,710
Growing degree days, base 45°F
3,627
Growing degree days, base 50°F
2,678
Growing degree days, base 55°F
1,861
Growing degree days, base 60°F
1,160

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30000
February1,12000
March942119
April564259
May24632280
June38131543
July12213666
August22163606
September14159373
October4565115
November792018
December1,10400

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 16 km from Springport. 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 USC00202437 (Eaton Rapids). Public domain.