Delta Junction climate

Delta Junction Frost Dates and Growing Season

NOAA 1991-2020 normals for Delta 5 Ne, 7.7 km from Delta Junction, elevation 1060 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Delta 5 Ne. 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 4 and the first fall freeze around August 22, a growing season of about 75 days.

Median at 32°F
last June 4, first August 22
Median at 28°F
last May 24, first September 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°F–––––––––
32°FJul 17Jun 20Jun 13Jun 8Jun 4Jun 1May 30May 28May 25
28°FJun 5Jun 1May 29May 26May 24May 21May 18May 16May 12
24°FMay 28May 22May 18May 15May 13May 10May 8May 5May 1
20°FMay 16May 11May 8May 5May 3May 1Apr 28Apr 23Apr 18
16°FMay 5May 2Apr 29Apr 26Apr 23Apr 20Apr 16Apr 13Apr 9

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 7Aug 11Aug 15Aug 19Aug 22Aug 25Aug 28Sep 1Sep 4
28°FAug 15Aug 20Aug 25Aug 29Sep 1Sep 3Sep 6Sep 10Sep 16
24°FAug 28Sep 2Sep 5Sep 8Sep 12Sep 15Sep 18Sep 23Sep 27
20°FSep 10Sep 14Sep 18Sep 21Sep 25Sep 27Sep 30Oct 3Oct 8
16°FSep 17Sep 23Sep 27Sep 30Oct 2Oct 4Oct 8Oct 12Oct 16

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°F736457514641363226
32°F959085807570665948
28°F1181121081039996918678
24°F144136131127123119114108100
20°F165159153149145141137131124
16°F181175170166163158154149143

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
13,685
Cooling degree days, base 65°F
20
Growing degree days, base 40°F
1,969
Growing degree days, base 45°F
1,291
Growing degree days, base 50°F
744
Growing degree days, base 55°F
347
Growing degree days, base 60°F
111

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January2,17600
February1,72500
March1,62100
April97201
May555047
June2418226
July1768300
August3454152
September680017
October1,27102
November1,84200
December2,08200

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 7.7 km from Delta Junction. 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 USC00502350 (Delta 5 Ne). Public domain.