Elmendorf Air Force Base climate

Elmendorf Air Force Base Frost Dates and Growing Season

NOAA 1991-2020 normals for Ft Richardson Wtp, 3.5 km from Elmendorf Air Force Base, elevation 470 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ft Richardson Wtp. 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 9 and the first fall freeze around September 26, a growing season of about 138 days.

Median at 36°F
last May 25, first September 14
Median at 32°F
last May 9, first September 26
Median at 28°F
last April 28, first October 6

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 5Jun 1May 30May 28May 25May 23May 19May 16May 12
32°FMay 22May 17May 14May 12May 9May 6May 4May 1Apr 28
28°FMay 9May 5May 2Apr 30Apr 28Apr 25Apr 21Apr 17Apr 13
24°FApr 30Apr 25Apr 22Apr 19Apr 16Apr 13Apr 11Apr 8Apr 5
20°FApr 23Apr 18Apr 13Apr 10Apr 8Apr 6Apr 4Apr 2Mar 30
16°FApr 17Apr 11Apr 7Apr 5Apr 4Apr 2Mar 31Mar 27Mar 20

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 29Sep 2Sep 7Sep 10Sep 14Sep 16Sep 19Sep 22Sep 27
32°FSep 9Sep 16Sep 19Sep 23Sep 26Sep 28Oct 1Oct 4Oct 10
28°FSep 22Sep 28Oct 1Oct 4Oct 6Oct 9Oct 12Oct 15Oct 20
24°FOct 1Oct 6Oct 10Oct 13Oct 16Oct 19Oct 22Oct 25Oct 29
20°FOct 8Oct 14Oct 18Oct 21Oct 24Oct 26Oct 29Nov 2Nov 7
16°FOct 17Oct 22Oct 25Oct 28Oct 31Nov 3Nov 6Nov 10Nov 14

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°F1291231191151111071039892
32°F157150145142138134130125119
28°F180173169165162158154149143
24°F198193189185181177173169162
20°F213208204200197193189185177
16°F228221216212208205201197191

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
10,542
Cooling degree days, base 65°F
8
Growing degree days, base 40°F
2,053
Growing degree days, base 45°F
1,282
Growing degree days, base 50°F
668
Growing degree days, base 55°F
252
Growing degree days, base 60°F
62

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,55600
February1,26000
March1,27400
April85402
May553032
June3082157
July2165255
August2831187
September519034
October93802
November1,30900
December1,47100

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 3.5 km from Elmendorf Air Force Base. 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 USC00503163 (Ft Richardson Wtp). Public domain.