Milan climate

Milan Frost Dates and Growing Season

NOAA 1991-2020 normals for Grants AP, 0.8 km from Milan, elevation 6520 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Grants AP. 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 17 and the first fall freeze around October 3, a growing season of about 137 days.

Median at 36°F
last May 31, first September 25
Median at 32°F
last May 17, first October 3
Median at 28°F
last May 4, first October 11

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°FJun 10Jun 6Jun 3Jun 1May 31May 28May 24May 20May 15
32°FJun 1May 29May 24May 20May 17May 13May 10May 6Apr 30
28°FMay 21May 15May 11May 6May 4Apr 30Apr 28Apr 25Apr 21
24°FMay 11May 4Apr 30Apr 28Apr 24Apr 21Apr 17Apr 13Apr 8
20°FApr 29Apr 21Apr 17Apr 13Apr 10Apr 7Apr 2Mar 30Mar 23
16°FApr 11Apr 5Apr 1Mar 28Mar 23Mar 20Mar 15Mar 11Mar 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 13Sep 17Sep 20Sep 23Sep 25Sep 27Sep 29Oct 1Oct 5
32°FSep 21Sep 24Sep 28Oct 1Oct 3Oct 4Oct 6Oct 10Oct 14
28°FSep 30Oct 3Oct 5Oct 8Oct 11Oct 14Oct 17Oct 20Oct 23
24°FOct 5Oct 10Oct 14Oct 18Oct 20Oct 23Oct 26Oct 29Nov 2
20°FOct 13Oct 19Oct 23Oct 26Oct 29Nov 1Nov 3Nov 7Nov 12
16°FOct 23Oct 28Nov 1Nov 4Nov 8Nov 11Nov 15Nov 19Nov 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°F135129124121118114110106100
32°F156150146141137134129125118
28°F176170166162158154150145138
24°F198191185181178174169165157
20°F222214208204200195190185178
16°F250242237232227222217211202

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
5,359
Cooling degree days, base 65°F
681
Growing degree days, base 40°F
5,230
Growing degree days, base 45°F
3,991
Growing degree days, base 50°F
2,929
Growing degree days, base 55°F
2,023
Growing degree days, base 60°F
1,277

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,01500
February80401
March668016
April435090
May20021298
June24147573
July1269733
August4193654
September7550426
October3881131
November72808
December1,01800

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 0.8 km from Milan. 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 USC00293682 (Grants AP). Public domain.