Madison climate

Madison Frost Dates and Growing Season

NOAA 1991-2020 normals for Charmany Farm, 6.7 km from Madison, elevation 1046 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Charmany Farm. 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 28 and the first fall freeze around October 15, a growing season of about 169 days.

Median at 36°F
last May 7, first October 4
Median at 32°F
last April 28, first October 15
Median at 28°F
last April 17, first October 25

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 22May 17May 13May 10May 7May 4May 1Apr 29Apr 25
32°FMay 11May 6May 3Apr 30Apr 28Apr 25Apr 22Apr 19Apr 14
28°FMay 1Apr 26Apr 22Apr 20Apr 17Apr 14Apr 11Apr 7Apr 4
24°FApr 20Apr 15Apr 12Apr 9Apr 6Apr 4Apr 2Mar 31Mar 24
20°FApr 12Apr 7Apr 4Apr 2Mar 31Mar 27Mar 23Mar 19Mar 14
16°FApr 3Mar 31Mar 27Mar 24Mar 21Mar 18Mar 15Mar 11Mar 6

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 20Sep 25Sep 28Oct 1Oct 4Oct 6Oct 9Oct 12Oct 17
32°FSep 29Oct 5Oct 9Oct 12Oct 15Oct 18Oct 21Oct 24Oct 29
28°FOct 10Oct 16Oct 20Oct 22Oct 25Oct 27Oct 30Nov 1Nov 6
24°FOct 21Oct 27Oct 30Nov 1Nov 2Nov 5Nov 9Nov 13Nov 18
20°FOct 31Nov 3Nov 7Nov 10Nov 12Nov 15Nov 18Nov 22Nov 27
16°FNov 6Nov 11Nov 15Nov 18Nov 21Nov 24Nov 27Dec 1Dec 7

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°F168161156152149145141136130
32°F190182177173169164160155149
28°F209203198193190185182177169
24°F231224218214210207203198191
20°F250242238233229225221216208
16°F268259254250247241236232225

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
7,360
Cooling degree days, base 65°F
614
Growing degree days, base 40°F
4,619
Growing degree days, base 45°F
3,572
Growing degree days, base 50°F
2,645
Growing degree days, base 55°F
1,840
Growing degree days, base 60°F
1,159

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,45500
February1,21100
March990114
April585261
May26031263
June49131533
July9216673
August20169614
September14959369
October4866108
November876010
December1,26901

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 6.7 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 USC00471416 (Charmany Farm). Public domain.