Milton climate

Milton Frost Dates and Growing Season

NOAA 1991-2020 normals for Ft Atkinson, 15.9 km from Milton, elevation 800 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ft Atkinson. 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 13, a growing season of about 166 days.

Median at 36°F
last May 10, first October 2
Median at 32°F
last April 28, first October 13
Median at 28°F
last April 16, first October 24

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 14May 10May 7May 3Apr 30Apr 25
32°FMay 17May 10May 5May 1Apr 28Apr 25Apr 21Apr 18Apr 14
28°FMay 3Apr 28Apr 23Apr 20Apr 16Apr 12Apr 9Apr 6Apr 3
24°FApr 20Apr 15Apr 11Apr 8Apr 5Apr 3Apr 1Mar 28Mar 22
20°FApr 10Apr 4Apr 2Mar 31Mar 27Mar 24Mar 20Mar 16Mar 12
16°FMar 31Mar 27Mar 24Mar 20Mar 17Mar 14Mar 12Mar 9Mar 5

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 24Sep 28Sep 30Oct 2Oct 4Oct 6Oct 9Oct 14
32°FSep 29Oct 3Oct 6Oct 10Oct 13Oct 16Oct 19Oct 21Oct 26
28°FOct 7Oct 14Oct 18Oct 22Oct 24Oct 26Oct 29Nov 1Nov 6
24°FOct 22Oct 28Oct 31Nov 1Nov 4Nov 7Nov 10Nov 14Nov 19
20°FNov 1Nov 5Nov 8Nov 12Nov 15Nov 18Nov 21Nov 24Nov 29
16°FNov 8Nov 13Nov 17Nov 21Nov 24Nov 27Nov 29Dec 2Dec 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°F163158153149145141137132125
32°F185179174170166162157152145
28°F209203198193189185181174166
24°F232225221216212209204199194
20°F253247241237233230226221213
16°F271264259255251247242238232

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
7,101
Cooling degree days, base 65°F
672
Growing degree days, base 40°F
4,765
Growing degree days, base 45°F
3,695
Growing degree days, base 50°F
2,751
Growing degree days, base 55°F
1,931
Growing degree days, base 60°F
1,233

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42000
February1,18401
March957115
April557472
May24942281
June46147551
July9229685
August18176623
September14067385
October4637121
November836016
December1,22301

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 15.9 km from Milton. 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 USC00472869 (Ft Atkinson). Public domain.