Pinckney climate

Pinckney Frost Dates and Growing Season

NOAA 1991-2020 normals for Howell Wwtp, 15.3 km from Pinckney, elevation 917 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Howell Wwtp. 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 4 and the first fall freeze around October 7, a growing season of about 156 days.

Median at 36°F
last May 16, first September 29
Median at 32°F
last May 4, first October 7
Median at 28°F
last April 24, first October 20

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 31May 27May 23May 19May 16May 13May 8May 4Apr 30
32°FMay 21May 16May 11May 7May 4Apr 30Apr 28Apr 24Apr 20
28°FMay 11May 5Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 11
24°FApr 28Apr 22Apr 18Apr 16Apr 13Apr 10Apr 7Apr 4Mar 31
20°FApr 16Apr 10Apr 6Apr 4Apr 2Mar 31Mar 28Mar 24Mar 18
16°FApr 4Apr 1Mar 31Mar 28Mar 25Mar 21Mar 17Mar 15Mar 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 17Sep 22Sep 25Sep 27Sep 29Oct 1Oct 4Oct 6Oct 10
32°FSep 27Sep 30Oct 3Oct 5Oct 7Oct 10Oct 13Oct 16Oct 21
28°FOct 5Oct 10Oct 14Oct 17Oct 20Oct 23Oct 26Oct 30Nov 3
24°FOct 18Oct 24Oct 28Oct 31Nov 1Nov 4Nov 7Nov 11Nov 16
20°FOct 31Nov 3Nov 6Nov 10Nov 13Nov 15Nov 19Nov 24Nov 29
16°FNov 9Nov 15Nov 19Nov 22Nov 26Nov 30Dec 3Dec 7Dec 14

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°F155148144140136132128123116
32°F174168163159156152147143136
28°F196190185181178174169163157
24°F221215209205201197194188182
20°F244239233229225221216211205
16°F268261256251246242238233226

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
6,885
Cooling degree days, base 65°F
542
Growing degree days, base 40°F
4,556
Growing degree days, base 45°F
3,481
Growing degree days, base 50°F
2,543
Growing degree days, base 55°F
1,736
Growing degree days, base 60°F
1,057

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30801
February1,12800
March963117
April578265
May27327247
June60122512
July18190637
August24147587
September14950357
October4675108
November792012
December1,12401

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 15.3 km from Pinckney. 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 USC00203947 (Howell Wwtp). Public domain.