Brainerd climate

Brainerd Frost Dates and Growing Season

NOAA 1991-2020 normals for Brainerd, 1.7 km from Brainerd, elevation 1180 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Brainerd. 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 8 and the first fall freeze around September 29, a growing season of about 141 days.

Median at 36°F
last May 19, first September 20
Median at 32°F
last May 8, first September 29
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 1May 28May 25May 22May 19May 16May 13May 9May 5
32°FMay 21May 16May 13May 10May 8May 5May 3May 1Apr 28
28°FMay 11May 7May 4May 2Apr 30Apr 27Apr 24Apr 22Apr 17
24°FMay 1Apr 28Apr 24Apr 22Apr 19Apr 17Apr 14Apr 11Apr 7
20°FApr 23Apr 20Apr 16Apr 13Apr 11Apr 8Apr 6Apr 3Mar 31
16°FApr 18Apr 13Apr 9Apr 6Apr 4Apr 2Mar 31Mar 27Mar 20

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 11Sep 15Sep 18Sep 20Sep 23Sep 25Sep 28Oct 1
32°FSep 16Sep 21Sep 24Sep 27Sep 29Oct 1Oct 4Oct 7Oct 11
28°FSep 25Sep 30Oct 2Oct 5Oct 8Oct 11Oct 15Oct 18Oct 23
24°FOct 4Oct 9Oct 14Oct 17Oct 21Oct 24Oct 27Oct 31Nov 4
20°FOct 16Oct 22Oct 26Oct 30Nov 1Nov 3Nov 6Nov 10Nov 16
16°FOct 29Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 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°F141135131127123119116112105
32°F159153149145141138135130125
28°F179173168164161158153148141
24°F202195190185181178174169163
20°F221214210205202198194190183
16°F236230226222218214210206200

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
9,053
Cooling degree days, base 65°F
365
Growing degree days, base 40°F
3,840
Growing degree days, base 45°F
2,908
Growing degree days, base 50°F
2,084
Growing degree days, base 55°F
1,378
Growing degree days, base 60°F
797

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,74200
February1,45200
March1,19003
April723027
May33415194
June8572437
July26148587
August48100518
September23728264
October637152
November1,06403
December1,51600

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 1.7 km from Brainerd. 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 USC00210939 (Brainerd). Public domain.