Red Lake County climate

Red Lake County Frost Dates and Growing Season

NOAA 1991-2020 normals for Red Lake Falls, 14.2 km from Red Lake County, elevation 1038 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Red Lake Falls. 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 9 and the first fall freeze around September 30, a growing season of about 142 days.

Median at 36°F
last May 20, first September 20
Median at 32°F
last May 9, first September 30
Median at 28°F
last April 30, first October 8

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 3May 30May 26May 22May 20May 17May 14May 11May 7
32°FMay 24May 19May 15May 12May 9May 6May 4May 1Apr 27
28°FMay 13May 8May 5May 3Apr 30Apr 29Apr 25Apr 21Apr 16
24°FMay 5Apr 30Apr 27Apr 24Apr 21Apr 18Apr 14Apr 10Apr 7
20°FApr 25Apr 21Apr 17Apr 14Apr 11Apr 8Apr 6Apr 4Mar 31
16°FApr 18Apr 13Apr 10Apr 6Apr 4Apr 2Mar 31Mar 27Mar 21

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 6Sep 12Sep 15Sep 17Sep 20Sep 22Sep 24Sep 27Oct 1
32°FSep 16Sep 20Sep 24Sep 27Sep 30Oct 1Oct 4Oct 7Oct 11
28°FSep 25Sep 30Oct 2Oct 5Oct 8Oct 11Oct 14Oct 18Oct 22
24°FOct 3Oct 8Oct 12Oct 16Oct 19Oct 22Oct 26Oct 30Nov 3
20°FOct 14Oct 20Oct 24Oct 28Oct 31Nov 1Nov 5Nov 8Nov 13
16°FOct 25Oct 30Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 21

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°F141135130125122119115111103
32°F161155150146142139135130123
28°F180173168164161157153147141
24°F202195189184180176171166159
20°F218213209205200197192186178
16°F235229225219216212208203197

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
9,524
Cooling degree days, base 65°F
386
Growing degree days, base 40°F
3,811
Growing degree days, base 45°F
2,896
Growing degree days, base 50°F
2,088
Growing degree days, base 55°F
1,391
Growing degree days, base 60°F
816

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,82700
February1,54000
March1,26002
April731129
May34919200
June8977439
July32145578
August52114527
September24329262
October669249
November1,13601
December1,59800

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 14.2 km from Red Lake 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 USC00216787 (Red Lake Falls). Public domain.