Sauk County climate

Sauk County Frost Dates and Growing Season

NOAA 1991-2020 normals for Reedsburg, 11.5 km from Sauk County, elevation 926 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Reedsburg. 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 2 and the first fall freeze around October 7, a growing season of about 156 days.

Median at 36°F
last May 13, first September 29
Median at 32°F
last May 2, first October 7
Median at 28°F
last April 20, first October 18

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 26May 22May 18May 15May 13May 9May 7May 3Apr 30
32°FMay 16May 11May 7May 4May 2Apr 29Apr 26Apr 23Apr 18
28°FMay 5May 1Apr 27Apr 23Apr 20Apr 18Apr 15Apr 11Apr 7
24°FApr 24Apr 19Apr 16Apr 12Apr 9Apr 6Apr 4Apr 1Mar 27
20°FApr 14Apr 8Apr 4Apr 2Mar 31Mar 28Mar 24Mar 21Mar 15
16°FApr 4Mar 31Mar 28Mar 24Mar 22Mar 19Mar 15Mar 12Mar 8

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 15Sep 20Sep 23Sep 26Sep 29Oct 1Oct 3Oct 6Oct 9
32°FSep 23Sep 27Oct 1Oct 4Oct 7Oct 9Oct 12Oct 15Oct 20
28°FOct 2Oct 8Oct 12Oct 15Oct 18Oct 21Oct 24Oct 27Oct 31
24°FOct 16Oct 22Oct 25Oct 28Oct 30Nov 1Nov 3Nov 7Nov 13
20°FOct 29Nov 1Nov 4Nov 7Nov 10Nov 14Nov 16Nov 20Nov 25
16°FNov 5Nov 9Nov 13Nov 17Nov 20Nov 23Nov 26Nov 30Dec 4

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°F155149145141137133130124117
32°F176169163160156153149144138
28°F198191186182178174169164158
24°F221214209205202198193188181
20°F246240235230226222218213206
16°F266257252248243239235230223

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
7,376
Cooling degree days, base 65°F
587
Growing degree days, base 40°F
4,565
Growing degree days, base 45°F
3,517
Growing degree days, base 50°F
2,595
Growing degree days, base 55°F
1,796
Growing degree days, base 60°F
1,121

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,47400
February1,21200
March971114
April572265
May25233271
June46124528
July11214668
August25156595
September16453349
October508595
November87009
December1,27100

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 11.5 km from Sauk County. 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 USC00477052 (Reedsburg). Public domain.