Cohoe climate

Cohoe Frost Dates and Growing Season

NOAA 1991-2020 normals for Soldotna 5SSW, 11 km from Cohoe, elevation 180 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Soldotna 5SSW. 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 June 11 and the first fall freeze around September 1, a growing season of about 75 days.

Median at 32°F
last June 11, first September 1
Median at 28°F
last May 23, first September 16

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°F–––––––––
32°FJul 7Jun 26Jun 20Jun 15Jun 11Jun 7Jun 2May 30May 26
28°FJun 6Jun 1May 29May 26May 23May 20May 16May 13May 9
24°FMay 21May 14May 11May 8May 5May 2Apr 30Apr 26Apr 21
20°FMay 4Apr 30Apr 27Apr 24Apr 21Apr 17Apr 14Apr 10Apr 6
16°FApr 23Apr 19Apr 15Apr 12Apr 9Apr 6Apr 4Apr 2Mar 30

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°F–––––––––
32°FAug 11Aug 18Aug 24Aug 28Sep 1Sep 3Sep 6Sep 11Sep 18
28°FAug 28Sep 3Sep 6Sep 11Sep 16Sep 20Sep 24Sep 27Oct 2
24°FSep 11Sep 19Sep 24Sep 27Sep 30Oct 2Oct 5Oct 10Oct 18
20°FSep 25Oct 1Oct 3Oct 6Oct 9Oct 13Oct 17Oct 21Oct 27
16°FOct 2Oct 7Oct 11Oct 15Oct 19Oct 22Oct 26Oct 30Nov 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°F665750454035312621
32°F1009286807570645848
28°F1351291231181131091049888
24°F168161154149145141136130123
20°F193185181176172168162157150
16°F213205200196191187183177171

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
11,238
Cooling degree days, base 65°F
1
Growing degree days, base 40°F
1,604
Growing degree days, base 45°F
888
Growing degree days, base 50°F
373
Growing degree days, base 55°F
92
Growing degree days, base 60°F
10

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,61200
February1,29200
March1,30000
April89600
May64506
June411074
July3030166
August3680114
September573012
October96300
November1,34800
December1,52800

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 11 km from Cohoe. 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 USC00508615 (Soldotna 5SSW). Public domain.