Madison climate

Madison Frost Dates and Growing Season

NOAA 1991-2020 normals for Madison 2SE, 2.4 km from Madison, elevation 1643 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Madison 2SE. 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 5 and the first fall freeze around September 30, a growing season of about 148 days.

Median at 36°F
last May 14, first September 23
Median at 32°F
last May 5, first September 30
Median at 28°F
last April 27, first October 10

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 29May 25May 21May 18May 14May 12May 9May 6May 2
32°FMay 18May 14May 11May 7May 5May 2Apr 30Apr 27Apr 22
28°FMay 10May 5May 2Apr 30Apr 27Apr 24Apr 20Apr 16Apr 12
24°FMay 1Apr 27Apr 23Apr 20Apr 16Apr 13Apr 10Apr 7Apr 3
20°FApr 23Apr 18Apr 14Apr 11Apr 8Apr 5Apr 2Mar 30Mar 22
16°FApr 17Apr 11Apr 6Apr 3Apr 1Mar 29Mar 24Mar 19Mar 13

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 10Sep 15Sep 18Sep 20Sep 23Sep 26Sep 28Oct 1Oct 5
32°FSep 18Sep 22Sep 26Sep 28Sep 30Oct 3Oct 5Oct 9Oct 13
28°FSep 26Sep 30Oct 3Oct 6Oct 10Oct 13Oct 16Oct 19Oct 23
24°FOct 5Oct 11Oct 15Oct 18Oct 21Oct 24Oct 26Oct 29Nov 3
20°FOct 16Oct 22Oct 25Oct 28Oct 31Nov 2Nov 4Nov 7Nov 12
16°FOct 26Oct 31Nov 2Nov 5Nov 7Nov 10Nov 13Nov 17Nov 23

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°F147142138134130127122117110
32°F164159155151148145141136129
28°F185179174170166162158153146
24°F205199195190185181177172164
20°F225218212208203200196191184
16°F244236230224219215211206199

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
7,998
Cooling degree days, base 65°F
631
Growing degree days, base 40°F
4,504
Growing degree days, base 45°F
3,495
Growing degree days, base 50°F
2,597
Growing degree days, base 55°F
1,819
Growing degree days, base 60°F
1,160

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57000
February1,28800
March1,04409
April617263
May27931256
June58130522
July13233685
August26170609
September17060355
October556489
November97808
December1,40000

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 2.4 km from Madison. 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 USC00395090 (Madison 2SE). Public domain.