Salamatof climate

Salamatof Frost Dates and Growing Season

NOAA 1991-2020 normals for Kenai Muni AP, 5.9 km from Salamatof, elevation 91 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Kenai Muni AP. 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 24 and the first fall freeze around September 12, a growing season of about 110 days.

Median at 32°F
last May 24, first September 12
Median at 28°F
last May 5, first September 25

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°FJun 4May 31May 29May 26May 24May 21May 17May 13May 8
28°FMay 18May 14May 11May 8May 5May 2Apr 30Apr 27Apr 22
24°FMay 3Apr 30Apr 28Apr 24Apr 21Apr 18Apr 15Apr 13Apr 8
20°FApr 26Apr 20Apr 16Apr 13Apr 10Apr 8Apr 6Apr 3Apr 1
16°FApr 19Apr 13Apr 9Apr 6Apr 4Apr 3Apr 1Mar 29Mar 23

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 29Sep 1Sep 4Sep 7Sep 12Sep 15Sep 19Sep 23Sep 27
28°FSep 7Sep 13Sep 18Sep 22Sep 25Sep 28Oct 1Oct 5Oct 10
24°FSep 20Sep 26Oct 1Oct 3Oct 6Oct 9Oct 14Oct 17Oct 22
20°FOct 1Oct 5Oct 9Oct 13Oct 17Oct 20Oct 23Oct 28Nov 1
16°FOct 8Oct 15Oct 19Oct 23Oct 26Oct 29Nov 1Nov 4Nov 10

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°F958983797470645849
32°F1311241191151101051019689
28°F161155150146142137133128120
24°F187180175172168164160155147
20°F206200195191187183179173167
16°F222215210206202198193187180

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
10,693
Cooling degree days, base 65°F
1
Growing degree days, base 40°F
1,814
Growing degree days, base 45°F
1,053
Growing degree days, base 50°F
470
Growing degree days, base 55°F
119
Growing degree days, base 60°F
12

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,55300
February1,26400
March1,28500
April87000
May606012
June387084
July2780188
August3180153
September518031
October90402
November1,25500
December1,45600

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 5.9 km from Salamatof. 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 USW00026523 (Kenai Muni AP). Public domain.