Brodhead climate

Brodhead Frost Dates and Growing Season

NOAA 1991-2020 normals for Brodhead Wwtp, 0.9 km from Brodhead, elevation 780 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Brodhead 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 April 29 and the first fall freeze around October 12, a growing season of about 165 days.

Median at 36°F
last May 9, first October 1
Median at 32°F
last April 29, first October 12
Median at 28°F
last April 17, first October 22

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 19May 15May 12May 9May 6May 3Apr 30Apr 26
32°FMay 14May 7May 4May 1Apr 29Apr 26Apr 23Apr 19Apr 14
28°FMay 1Apr 27Apr 23Apr 20Apr 17Apr 14Apr 11Apr 7Apr 4
24°FApr 21Apr 16Apr 12Apr 8Apr 6Apr 3Apr 1Mar 30Mar 23
20°FApr 10Apr 5Apr 2Mar 31Mar 28Mar 24Mar 21Mar 17Mar 12
16°FApr 1Mar 28Mar 24Mar 21Mar 18Mar 15Mar 12Mar 9Mar 4

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 19Sep 24Sep 27Sep 29Oct 1Oct 3Oct 6Oct 10Oct 15
32°FSep 28Oct 1Oct 5Oct 8Oct 12Oct 14Oct 17Oct 20Oct 25
28°FOct 6Oct 13Oct 16Oct 20Oct 22Oct 25Oct 28Oct 31Nov 4
24°FOct 19Oct 24Oct 28Oct 31Nov 1Nov 5Nov 8Nov 12Nov 18
20°FNov 1Nov 4Nov 7Nov 11Nov 14Nov 17Nov 21Nov 24Nov 29
16°FNov 8Nov 12Nov 16Nov 20Nov 23Nov 26Nov 30Dec 3Dec 9

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°F164156152148144140136132125
32°F184178173168165161156151144
28°F207200196192187183178172166
24°F230224218214211206201197191
20°F252246239235230226223217209
16°F271264258253249245240235228

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
7,104
Cooling degree days, base 65°F
667
Growing degree days, base 40°F
4,769
Growing degree days, base 45°F
3,699
Growing degree days, base 50°F
2,750
Growing degree days, base 55°F
1,928
Growing degree days, base 60°F
1,229

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42700
February1,18401
March946011
April547374
May24042287
June41149558
July8226684
August17176623
September14364378
October4667120
November843015
December1,24001

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 0.9 km from Brodhead. 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 USC00471078 (Brodhead Wwtp). Public domain.