Morris climate

Morris Frost Dates and Growing Season

NOAA 1991-2020 normals for Emmons, 21.2 km from Morris, elevation 1225 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Emmons. 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 141 days.

Median at 36°F
last May 29, first September 22
Median at 32°F
last May 17, first October 3
Median at 28°F
last May 4, first October 16

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 2May 31May 29May 26May 23May 19May 14
32°FMay 30May 26May 23May 19May 17May 13May 10May 6Apr 30
28°FMay 19May 14May 10May 7May 4May 1Apr 28Apr 25Apr 21
24°FMay 8May 2Apr 28Apr 25Apr 22Apr 19Apr 16Apr 12Apr 7
20°FApr 21Apr 17Apr 13Apr 10Apr 7Apr 6Apr 3Apr 1Mar 29
16°FApr 11Apr 7Apr 4Apr 2Apr 1Mar 30Mar 26Mar 22Mar 18

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 13Sep 17Sep 20Sep 22Sep 25Sep 28Sep 30Oct 3
32°FSep 20Sep 24Sep 28Oct 1Oct 3Oct 5Oct 7Oct 12Oct 18
28°FOct 1Oct 4Oct 8Oct 12Oct 16Oct 20Oct 25Oct 31Nov 3
24°FOct 10Oct 17Oct 23Oct 28Nov 1Nov 3Nov 5Nov 9Nov 14
20°FOct 28Nov 1Nov 5Nov 8Nov 11Nov 13Nov 16Nov 20Nov 26
16°FNov 6Nov 10Nov 14Nov 17Nov 21Nov 24Nov 27Dec 1Dec 6

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°F13713012512011711310910597
32°F161154149144141137133128121
28°F188180174169164160155150143
24°F211205200194190186180174166
20°F237229224219215211207201194
16°F255247242239235232227223215

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
7,687
Cooling degree days, base 65°F
261
Growing degree days, base 40°F
3,840
Growing degree days, base 45°F
2,831
Growing degree days, base 50°F
1,963
Growing degree days, base 55°F
1,232
Growing degree days, base 60°F
656

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,37001
February1,19400
March1,09005
April677240
May35314180
June12648375
July4096521
August5875482
September21425274
October544274
November846011
December1,17501

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 21.2 km from Morris. 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 USC00305113 (Emmons). Public domain.