Brownstown climate

Brownstown Frost Dates and Growing Season

NOAA 1991-2020 normals for Brownstown 4 Sw, 4.6 km from Brownstown, elevation 530 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Brownstown 4 Sw. 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 3 and the first fall freeze around October 24, a growing season of about 202 days.

Median at 36°F
last April 18, first October 13
Median at 32°F
last April 3, first October 24
Median at 28°F
last March 27, first November 4

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 1Apr 26Apr 21Apr 18Apr 13Apr 9Apr 5Mar 31
32°FApr 25Apr 18Apr 12Apr 7Apr 3Apr 1Mar 29Mar 25Mar 19
28°FApr 13Apr 6Apr 1Mar 30Mar 27Mar 24Mar 21Mar 17Mar 10
24°FApr 2Mar 28Mar 24Mar 21Mar 17Mar 14Mar 10Mar 5Feb 28
20°FMar 25Mar 19Mar 15Mar 12Mar 7Mar 4Mar 1Feb 26Feb 18
16°FMar 17Mar 12Mar 7Mar 3Feb 28Feb 25Feb 19Feb 12Feb 6

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 27Oct 2Oct 7Oct 10Oct 13Oct 16Oct 19Oct 22Oct 28
32°FOct 9Oct 15Oct 19Oct 22Oct 24Oct 27Oct 30Nov 2Nov 8
28°FOct 21Oct 26Oct 30Nov 1Nov 4Nov 7Nov 12Nov 17Nov 25
24°FNov 1Nov 5Nov 8Nov 12Nov 16Nov 22Nov 27Dec 2Dec 7
20°FNov 9Nov 14Nov 19Nov 25Nov 29Dec 2Dec 6Dec 11Dec 19
16°FNov 16Nov 23Nov 28Dec 2Dec 7Dec 12Dec 17Dec 22Dec 29

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°F201193188183177173168162153
32°F225217211206202197191185176
28°F248240235229224219215209200
24°F272262257251245241236230222
20°F293284277270265259254247239
16°F312301295290285280274266255

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
5,046
Cooling degree days, base 65°F
1,274
Growing degree days, base 40°F
6,340
Growing degree days, base 45°F
5,061
Growing degree days, base 50°F
3,921
Growing degree days, base 55°F
2,908
Growing degree days, base 60°F
2,019

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11104
February87608
March666159
April32126213
May103100464
June12292730
July1368832
August5308769
September58153548
October31024230
November627258
December95606

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 4.6 km from Brownstown. 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 USC00111020 (Brownstown 4 Sw). Public domain.