Ninilchik climate

Ninilchik Frost Dates and Growing Season

NOAA 1991-2020 normals for Homer 8 Nw, 34 km from Ninilchik, elevation 1080 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Homer 8 Nw. 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 16 and the first fall freeze around September 30, a growing season of about 136 days.

Median at 36°F
last June 3, first September 17
Median at 32°F
last May 16, first September 30
Median at 28°F
last April 29, first October 11

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°FJun 20Jun 14Jun 10Jun 6Jun 3Jun 1May 30May 27May 22
32°FMay 30May 26May 22May 19May 16May 13May 10May 6May 1
28°FMay 12May 8May 5May 2Apr 29Apr 25Apr 21Apr 17Apr 12
24°FApr 30Apr 24Apr 20Apr 16Apr 13Apr 10Apr 8Apr 5Apr 2
20°FApr 19Apr 14Apr 10Apr 7Apr 5Apr 3Apr 1Mar 29Mar 22
16°FApr 11Apr 7Apr 4Apr 1Mar 30Mar 26Mar 22Mar 18Mar 12

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°FAug 31Sep 5Sep 9Sep 14Sep 17Sep 20Sep 23Sep 26Sep 30
32°FSep 16Sep 21Sep 25Sep 28Sep 30Oct 2Oct 5Oct 9Oct 14
28°FSep 28Oct 1Oct 5Oct 8Oct 11Oct 14Oct 17Oct 21Oct 25
24°FOct 6Oct 11Oct 15Oct 19Oct 21Oct 24Oct 27Nov 1Nov 7
20°FOct 15Oct 21Oct 25Oct 28Nov 1Nov 4Nov 8Nov 12Nov 17
16°FOct 24Oct 30Nov 2Nov 6Nov 11Nov 14Nov 18Nov 22Nov 29

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°F12211611110710399948980
32°F158150144140136132127123115
28°F186179174170165162158153146
24°F212206200195190186181175169
20°F232225219215210206201195187
16°F253243237232228223218212204

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
10,107
Cooling degree days, base 65°F
1
Growing degree days, base 40°F
1,522
Growing degree days, base 45°F
813
Growing degree days, base 50°F
312
Growing degree days, base 55°F
76
Growing degree days, base 60°F
13

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29600
February1,10500
March1,18300
April88501
May662013
June456053
July3501126
August3720104
September549014
October87700
November1,11700
December1,25600

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 34 km from Ninilchik. 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 USC00503672 (Homer 8 Nw). Public domain.