Linn climate

Linn Frost Dates and Growing Season

NOAA 1991-2020 normals for Freedom, 13.2 km from Linn, elevation 805 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Freedom. 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 11 and the first fall freeze around October 21, a growing season of about 191 days.

Median at 36°F
last April 27, first October 12
Median at 32°F
last April 11, first October 21
Median at 28°F
last March 31, first November 1

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 14May 8May 4Apr 30Apr 27Apr 23Apr 19Apr 15Apr 10
32°FApr 30Apr 25Apr 20Apr 15Apr 11Apr 8Apr 5Apr 1Mar 28
28°FApr 19Apr 11Apr 6Apr 3Mar 31Mar 28Mar 25Mar 20Mar 14
24°FApr 5Mar 31Mar 27Mar 24Mar 20Mar 17Mar 13Mar 9Mar 2
20°FMar 28Mar 21Mar 17Mar 13Mar 9Mar 5Mar 2Feb 26Feb 20
16°FMar 18Mar 13Mar 8Mar 5Mar 2Feb 28Feb 24Feb 17Feb 10

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 28Oct 2Oct 6Oct 9Oct 12Oct 15Oct 17Oct 20Oct 25
32°FOct 6Oct 12Oct 15Oct 18Oct 21Oct 25Oct 27Oct 30Nov 4
28°FOct 18Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 10Nov 16
24°FOct 31Nov 2Nov 5Nov 8Nov 11Nov 15Nov 19Nov 24Dec 1
20°FNov 6Nov 12Nov 16Nov 20Nov 24Nov 28Dec 1Dec 5Dec 11
16°FNov 14Nov 23Nov 26Nov 30Dec 3Dec 7Dec 10Dec 16Dec 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°F188181176172168163159154147
32°F212204199195191187183177169
28°F237230223218214209204199192
24°F261252246241236232227220210
20°F281273267263257252247241232
16°F302293287281276271265258250

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
4,932
Cooling degree days, base 65°F
1,240
Growing degree days, base 40°F
6,385
Growing degree days, base 45°F
5,080
Growing degree days, base 50°F
3,913
Growing degree days, base 55°F
2,884
Growing degree days, base 60°F
1,991

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07406
February844016
March644574
April32426214
May11892442
June14242678
July1369832
August3328790
September63144532
October29831247
November611369
December938012

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 13.2 km from Linn. 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 USC00233043 (Freedom). Public domain.