Bronson climate

Bronson Frost Dates and Growing Season

NOAA 1991-2020 normals for Usher Twr, 17.7 km from Bronson, elevation 33 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Usher Twr. 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 February 28 and the first fall freeze around December 2, a growing season of about 279 days.

Median at 36°F
last March 14, first November 19
Median at 32°F
last February 28, first December 2
Median at 28°F
last February 6, first December 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°FApr 7Mar 30Mar 23Mar 19Mar 14Mar 10Mar 5Feb 28Feb 20
32°FMar 22Mar 14Mar 8Mar 4Feb 28Feb 23Feb 17Feb 9Jan 31
28°FMar 6Feb 27Feb 19Feb 12Feb 6Feb 1Jan 27Jan 19Jan 7
24°FFeb 20Feb 10Feb 4Jan 31Jan 26Jan 18Jan 10Jan 4Dec 26
20°FFeb 16Feb 6Jan 31Jan 24Jan 17Jan 11Jan 6Dec 31Dec 21
16°F–––––––––

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°FNov 2Nov 7Nov 12Nov 16Nov 19Nov 23Nov 28Dec 3Dec 10
32°FNov 12Nov 19Nov 24Nov 28Dec 2Dec 6Dec 13Dec 23Jan 4
28°FNov 26Dec 3Dec 8Dec 16Dec 27Jan 3Jan 8Jan 17Jan 31
24°FDec 8Dec 18Dec 28Jan 3Jan 8Jan 13Jan 21Jan 31Feb 7
20°FDec 15Dec 28Jan 1Jan 7Jan 11Jan 17Jan 24Feb 3Feb 14
16°F–––––––––

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°F282270263256250244239231222
32°F315304296288279272265257246
28°F355341333326318310302292279
24°F365365365359349341334325314
20°F365365365365365365365358340
16°F365365365365365365365365365

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
92% of years
24°F or colder
64% of years
20°F or colder
26% of years
16°F or colder
3% 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
1,097
Cooling degree days, base 65°F
2,656
Growing degree days, base 40°F
10,694
Growing degree days, base 45°F
8,897
Growing degree days, base 50°F
7,155
Growing degree days, base 55°F
5,506
Growing degree days, base 60°F
3,993

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January31715216
February20824256
March12460407
April34137554
May2297760
June0429879
July0487952
August0488953
September0407856
October22225668
November13162388
December25925266

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 17.7 km from Bronson. 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 USC00089120 (Usher Twr). Public domain.