Cottage Grove climate

Cottage Grove Frost Dates and Growing Season

NOAA 1991-2020 normals for Cottage Grove 2E, 2.6 km from Cottage Grove, elevation 595 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cottage Grove 2E. 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 24 and the first fall freeze around October 25, a growing season of about 183 days.

Median at 36°F
last May 12, first October 1
Median at 32°F
last April 24, first October 25
Median at 28°F
last March 23, first November 18

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 30May 23May 19May 15May 12May 9May 5May 1Apr 26
32°FMay 10May 4May 1Apr 28Apr 24Apr 20Apr 15Apr 9Mar 31
28°FApr 22Apr 13Apr 3Mar 29Mar 23Mar 15Mar 7Feb 28Feb 21
24°FMar 11Mar 1Feb 26Feb 21Feb 16Feb 8Jan 29Jan 12Dec 29
20°FFeb 23Feb 17Feb 7Jan 25Jan 14Jan 4Dec 30Dec 22Dec 11
16°FFeb 11Jan 26Jan 11Jan 1Dec 30Dec 25Dec 20Dec 13Dec 6

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 7Sep 14Sep 22Sep 29Oct 1Oct 6Oct 12Oct 17Oct 26
32°FSep 30Oct 9Oct 15Oct 20Oct 25Oct 29Nov 1Nov 7Nov 16
28°FOct 21Oct 30Nov 4Nov 10Nov 18Nov 24Nov 30Dec 6Dec 17
24°FNov 6Nov 20Dec 1Dec 7Dec 15Dec 21Dec 28Jan 6Jan 28
20°FNov 24Dec 6Dec 13Dec 21Dec 26Jan 1Jan 9Jan 21Feb 11
16°FDec 3Dec 10Dec 16Dec 22Dec 27Dec 31Jan 4Jan 19Feb 3

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°F169159151145140135128120108
32°F216207197189183176170162151
28°F279266255247239231223215200
24°F352335324314307298286273254
20°F365365365363353342330316307
16°F365365365365365365365355338

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
95% of years
20°F or colder
62% of years
16°F or colder
29% 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
4,854
Cooling degree days, base 65°F
225
Growing degree days, base 40°F
4,697
Growing degree days, base 45°F
3,256
Growing degree days, base 50°F
2,107
Growing degree days, base 55°F
1,237
Growing degree days, base 60°F
614

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January75204
February62308
March595020
April459063
May2955188
June15722316
July4088513
August3885511
September13524340
October3860116
November599023
December77505

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 2.6 km from Cottage Grove. 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 USC00351897 (Cottage Grove 2E). Public domain.