Shepherd climate

Shepherd Frost Dates and Growing Season

NOAA 1991-2020 normals for Central Michigan Univ, 9 km from Shepherd, elevation 795 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Central Michigan Univ. 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 20, a growing season of about 171 days.

Median at 36°F
last May 10, first October 7
Median at 32°F
last April 30, first October 20
Median at 28°F
last April 19, first November 3

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 24May 21May 17May 14May 10May 7May 5May 1Apr 28
32°FMay 16May 10May 6May 3Apr 30Apr 28Apr 25Apr 22Apr 17
28°FMay 4Apr 30Apr 26Apr 22Apr 19Apr 16Apr 13Apr 9Apr 4
24°FApr 21Apr 17Apr 13Apr 9Apr 6Apr 4Apr 1Mar 30Mar 24
20°FApr 10Apr 5Apr 2Apr 1Mar 30Mar 26Mar 23Mar 18Mar 14
16°FApr 2Mar 30Mar 26Mar 23Mar 20Mar 17Mar 14Mar 10Mar 5

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 25Sep 30Oct 2Oct 5Oct 7Oct 10Oct 13Oct 16Oct 22
32°FOct 5Oct 10Oct 13Oct 17Oct 20Oct 23Oct 26Oct 30Nov 3
28°FOct 20Oct 25Oct 29Nov 1Nov 3Nov 5Nov 8Nov 12Nov 17
24°FNov 2Nov 5Nov 9Nov 11Nov 15Nov 17Nov 21Nov 24Dec 1
20°FNov 9Nov 15Nov 18Nov 22Nov 25Nov 28Dec 1Dec 5Dec 12
16°FNov 19Nov 24Nov 28Dec 1Dec 4Dec 8Dec 14Dec 18Dec 24

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°F167161156153149145141136130
32°F192184179175171167163158152
28°F217210204200196193189183177
24°F242236230226222218214208201
20°F262255250246241237232227221
16°F283276270265260256252246239

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
6,899
Cooling degree days, base 65°F
661
Growing degree days, base 40°F
4,685
Growing degree days, base 45°F
3,624
Growing degree days, base 50°F
2,696
Growing degree days, base 55°F
1,893
Growing degree days, base 60°F
1,209

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,31100
February1,13700
March988111
April600356
May26434264
June49139540
July9232688
August18181628
September13766386
October4595110
November800013
December1,12800

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 km from Shepherd. 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 USC00205662 (Central Michigan Univ). Public domain.