Itasca County climate

Itasca County Frost Dates and Growing Season

NOAA 1991-2020 normals for Marcell 5NE, 13.5 km from Itasca County, elevation 1387 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Marcell 5NE. 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 14 and the first fall freeze around October 2, a growing season of about 140 days.

Median at 36°F
last May 25, first September 24
Median at 32°F
last May 14, first October 2
Median at 28°F
last May 3, first October 14

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 8Jun 3May 31May 28May 25May 23May 20May 16May 11
32°FMay 30May 25May 21May 17May 14May 11May 7May 4Apr 30
28°FMay 20May 13May 9May 6May 3Apr 30Apr 28Apr 24Apr 20
24°FMay 8May 2Apr 29Apr 25Apr 23Apr 20Apr 18Apr 15Apr 11
20°FApr 25Apr 21Apr 19Apr 16Apr 14Apr 11Apr 9Apr 6Apr 3
16°FApr 19Apr 15Apr 12Apr 9Apr 7Apr 5Apr 3Apr 1Mar 29

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 8Sep 14Sep 18Sep 20Sep 24Sep 26Sep 28Oct 1Oct 5
32°FSep 20Sep 25Sep 28Oct 1Oct 2Oct 5Oct 9Oct 12Oct 16
28°FOct 1Oct 5Oct 9Oct 11Oct 14Oct 18Oct 20Oct 24Oct 28
24°FOct 12Oct 17Oct 21Oct 24Oct 27Oct 30Nov 1Nov 4Nov 8
20°FOct 23Oct 29Nov 1Nov 3Nov 5Nov 7Nov 9Nov 12Nov 16
16°FOct 31Nov 3Nov 5Nov 8Nov 10Nov 13Nov 15Nov 18Nov 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°F137132127124120116112107101
32°F160153148144140136132127119
28°F181174170166162159154149141
24°F203197192188184180176171164
20°F220215211206203199196191186
16°F232227223219216213210205200

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
9,879
Cooling degree days, base 65°F
231
Growing degree days, base 40°F
3,374
Growing degree days, base 45°F
2,502
Growing degree days, base 50°F
1,736
Growing degree days, base 55°F
1,089
Growing degree days, base 60°F
578

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,84400
February1,54700
March1,27700
April807014
May4247139
June14047361
July5292505
August7670459
September27215221
October690037
November1,14300
December1,60700

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 13.5 km from Itasca County. 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 USC00215175 (Marcell 5NE). Public domain.