Minneapolis climate

Minneapolis Frost Dates and Growing Season

NOAA 1991-2020 normals for Lower St Anthony Falls, 1.4 km from Minneapolis, elevation 754 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lower St Anthony 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 April 23 and the first fall freeze around October 16, a growing season of about 175 days.

Median at 36°F
last May 4, first October 5
Median at 32°F
last April 23, first October 16
Median at 28°F
last April 14, first October 27

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°FMay 21May 14May 10May 6May 4May 1Apr 29Apr 26Apr 20
32°FMay 7May 2Apr 30Apr 26Apr 23Apr 21Apr 18Apr 15Apr 10
28°FApr 27Apr 23Apr 20Apr 17Apr 14Apr 12Apr 8Apr 6Apr 2
24°FApr 19Apr 15Apr 11Apr 8Apr 5Apr 3Apr 1Mar 28Mar 22
20°FApr 11Apr 6Apr 3Apr 1Mar 30Mar 27Mar 23Mar 19Mar 13
16°FApr 5Apr 1Mar 29Mar 26Mar 22Mar 19Mar 15Mar 11Mar 7

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 23Sep 28Sep 30Oct 3Oct 5Oct 8Oct 12Oct 15Oct 20
32°FOct 2Oct 6Oct 10Oct 14Oct 16Oct 19Oct 22Oct 26Oct 30
28°FOct 12Oct 18Oct 21Oct 24Oct 27Oct 30Nov 1Nov 5Nov 9
24°FOct 21Oct 27Oct 31Nov 2Nov 5Nov 7Nov 10Nov 14Nov 20
20°FOct 30Nov 3Nov 6Nov 10Nov 12Nov 15Nov 19Nov 23Nov 28
16°FNov 6Nov 11Nov 15Nov 18Nov 22Nov 24Nov 27Nov 30Dec 5

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°F172167162158154150146142134
32°F192187182178175171167162155
28°F214207202198195191187181175
24°F232225220216212207203197191
20°F250243236232227223218213205
16°F265257252247243238234227219

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
7,699
Cooling degree days, base 65°F
734
Growing degree days, base 40°F
4,743
Growing degree days, base 45°F
3,720
Growing degree days, base 50°F
2,799
Growing degree days, base 55°F
1,991
Growing degree days, base 60°F
1,298

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,55300
February1,27700
March1,02309
April584268
May22839296
June41147556
July5271731
August13199651
September13870389
October524594
November95005
December1,36400

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 1.4 km from Minneapolis. 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 USC00214884 (Lower St Anthony Falls). Public domain.