Madison climate

Madison Frost Dates and Growing Season

NOAA 1991-2020 normals for Somerset, 15 km from Madison, elevation 510 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Somerset. 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 17 and the first fall freeze around October 22, a growing season of about 188 days.

Median at 36°F
last April 29, first October 13
Median at 32°F
last April 17, first October 22
Median at 28°F
last April 3, first November 1

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 17May 10May 6May 2Apr 29Apr 25Apr 21Apr 18Apr 14
32°FMay 6Apr 28Apr 22Apr 19Apr 17Apr 14Apr 10Apr 6Apr 1
28°FApr 20Apr 14Apr 9Apr 6Apr 3Apr 1Mar 30Mar 26Mar 19
24°FApr 5Apr 1Mar 30Mar 27Mar 23Mar 19Mar 15Mar 11Mar 4
20°FMar 27Mar 22Mar 18Mar 14Mar 11Mar 8Mar 4Feb 28Feb 21
16°FMar 18Mar 11Mar 6Mar 3Feb 28Feb 22Feb 16Feb 10Feb 2

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°FOct 2Oct 5Oct 8Oct 11Oct 13Oct 16Oct 19Oct 22Oct 26
32°FOct 9Oct 13Oct 17Oct 20Oct 22Oct 25Oct 28Oct 31Nov 3
28°FOct 17Oct 23Oct 26Oct 29Nov 1Nov 3Nov 5Nov 9Nov 13
24°FOct 28Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 23Dec 1
20°FNov 8Nov 14Nov 18Nov 23Nov 27Dec 1Dec 4Dec 10Dec 19
16°FNov 21Dec 1Dec 4Dec 8Dec 13Dec 18Dec 23Dec 30Jan 8

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°F188180175171167163158153146
32°F208201196192188184179173165
28°F230223217214210207202197189
24°F258251243238234230225219212
20°F287278271266260256249242234
16°F322309302295289283276269258

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
4,551
Cooling degree days, base 65°F
1,150
Growing degree days, base 40°F
6,344
Growing degree days, base 45°F
4,994
Growing degree days, base 50°F
3,803
Growing degree days, base 55°F
2,765
Growing degree days, base 60°F
1,882

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January947010
February776012
March632259
April31821202
May11783433
June13237673
July1348812
August3305767
September54136533
October28918225
November568160
December834016

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 km from Madison. 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 USC00447904 (Somerset). Public domain.