Fergus Falls climate

Fergus Falls Frost Dates and Growing Season

NOAA 1991-2020 normals for Fergus Falls, 3.2 km from Fergus Falls, elevation 1250 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fergus 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 4 and the first fall freeze around October 5, a growing season of about 152 days.

Median at 36°F
last May 14, first September 27
Median at 32°F
last May 4, first October 5
Median at 28°F
last April 26, first October 15

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

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 13Sep 18Sep 21Sep 24Sep 27Sep 29Oct 1Oct 5Oct 9
32°FSep 22Sep 27Sep 30Oct 2Oct 5Oct 7Oct 11Oct 14Oct 19
28°FOct 1Oct 5Oct 9Oct 12Oct 15Oct 19Oct 22Oct 25Oct 28
24°FOct 10Oct 15Oct 19Oct 22Oct 25Oct 28Oct 31Nov 3Nov 8
20°FOct 21Oct 25Oct 29Nov 1Nov 3Nov 5Nov 9Nov 12Nov 17
16°FOct 29Nov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 19Nov 25

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°F152146142138134131127123116
32°F172163159155152149145140134
28°F193185180176172167163158151
24°F213205200196193188184178172
20°F229221217212208204200196189
16°F243236231227223218214209202

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
8,882
Cooling degree days, base 65°F
521
Growing degree days, base 40°F
4,148
Growing degree days, base 45°F
3,200
Growing degree days, base 50°F
2,356
Growing degree days, base 55°F
1,621
Growing degree days, base 60°F
996

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,73600
February1,46300
March1,18301
April680141
May30826231
June71110490
July20198643
August39139566
September19944314
October611367
November1,05903
December1,51400

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 3.2 km from Fergus Falls. 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 USC00212768 (Fergus Falls). Public domain.