Spring Arbor climate

Spring Arbor Frost Dates and Growing Season

NOAA 1991-2020 normals for Jackson Reynolds Fld, 9.9 km from Spring Arbor, elevation 998 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Jackson Reynolds Fld. 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 1 and the first fall freeze around October 14, a growing season of about 164 days.

Median at 36°F
last May 13, first October 3
Median at 32°F
last May 1, first October 14
Median at 28°F
last April 20, first October 28

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 29May 23May 20May 16May 13May 9May 5May 1Apr 27
32°FMay 18May 12May 7May 4May 1Apr 28Apr 25Apr 22Apr 16
28°FMay 6May 1Apr 27Apr 22Apr 20Apr 17Apr 14Apr 10Apr 4
24°FApr 23Apr 18Apr 15Apr 10Apr 7Apr 4Apr 2Mar 30Mar 24
20°FApr 12Apr 6Apr 2Mar 31Mar 29Mar 25Mar 22Mar 18Mar 14
16°FApr 1Mar 28Mar 24Mar 21Mar 19Mar 16Mar 13Mar 10Mar 3

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 20Sep 24Sep 28Oct 1Oct 3Oct 5Oct 7Oct 11Oct 15
32°FSep 30Oct 5Oct 8Oct 11Oct 14Oct 17Oct 20Oct 23Oct 28
28°FOct 12Oct 18Oct 22Oct 25Oct 28Oct 31Nov 2Nov 5Nov 11
24°FOct 29Nov 1Nov 3Nov 5Nov 8Nov 11Nov 15Nov 19Nov 25
20°FNov 5Nov 9Nov 14Nov 18Nov 21Nov 25Nov 29Dec 3Dec 9
16°FNov 14Nov 20Nov 24Nov 28Dec 1Dec 4Dec 8Dec 13Dec 19

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°F163156152147143139135130122
32°F187180175169164160156150142
28°F210203198193189184179173165
24°F235227222219215212207202192
20°F261253247242237233229224218
16°F282274269264260255249243235

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
6,470
Cooling degree days, base 65°F
635
Growing degree days, base 40°F
4,875
Growing degree days, base 45°F
3,753
Growing degree days, base 50°F
2,767
Growing degree days, base 55°F
1,917
Growing degree days, base 60°F
1,199

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,25801
February1,07701
March900121
April520484
May23440291
June46136540
July9213670
August18170617
September13463385
October4347131
November753024
December1,08803

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 9.9 km from Spring Arbor. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00014833 (Jackson Reynolds Fld). Public domain.