South Van Horn climate

South Van Horn Frost Dates and Growing Season

NOAA 1991-2020 normals for Fairbanks Midtown, 2.7 km from South Van Horn, elevation 440 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fairbanks Midtown. 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 13 and the first fall freeze around September 10, a growing season of about 119 days.

Median at 36°F
last May 24, first August 31
Median at 32°F
last May 13, first September 10
Median at 28°F
last May 5, first September 20

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 4Jun 1May 29May 27May 24May 21May 18May 15May 11
32°FMay 28May 22May 18May 15May 13May 11May 8May 6May 3
28°FMay 17May 13May 10May 7May 5May 3May 1Apr 29Apr 24
24°FMay 9May 5May 2Apr 30Apr 28Apr 26Apr 23Apr 19Apr 14
20°FMay 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 13Apr 9
16°FApr 28Apr 23Apr 20Apr 17Apr 14Apr 12Apr 10Apr 8Apr 5

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 19Aug 24Aug 26Aug 29Aug 31Sep 1Sep 4Sep 8Sep 12
32°FAug 28Sep 1Sep 4Sep 7Sep 10Sep 13Sep 16Sep 19Sep 23
28°FSep 5Sep 11Sep 15Sep 17Sep 20Sep 22Sep 25Sep 28Oct 1
24°FSep 15Sep 20Sep 24Sep 27Sep 29Oct 1Oct 3Oct 7Oct 11
20°FSep 25Sep 28Oct 1Oct 3Oct 6Oct 8Oct 11Oct 14Oct 19
16°FSep 30Oct 4Oct 7Oct 10Oct 13Oct 16Oct 18Oct 21Oct 25

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°F1141091051019895928782
32°F136130126122119115112108102
28°F154149145140137134131126120
24°F171165161157153150147142135
20°F186180176172169166162158151
16°F196191186184180177174170164

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
13,140
Cooling degree days, base 65°F
70
Growing degree days, base 40°F
2,430
Growing degree days, base 45°F
1,698
Growing degree days, base 50°F
1,070
Growing degree days, base 55°F
581
Growing degree days, base 60°F
247

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January2,21900
February1,73800
March1,60700
April92305
May461192
June14828334
July10032397
August2709214
September599026
October1,19202
November1,78900
December2,09400

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 2.7 km from South Van Horn. 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 USC00502970 (Fairbanks Midtown). Public domain.