Fairbank climate

Fairbank Frost Dates and Growing Season

NOAA 1991-2020 normals for Oelwein 1E, 14.8 km from Fairbank, elevation 1165 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Oelwein 1E. 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 April 27 and the first fall freeze around October 13, a growing season of about 169 days.

Median at 36°F
last May 5, first October 3
Median at 32°F
last April 27, first October 13
Median at 28°F
last April 15, first October 22

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

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°FSep 20Sep 25Sep 28Oct 1Oct 3Oct 5Oct 8Oct 12Oct 16
32°FSep 30Oct 4Oct 7Oct 10Oct 13Oct 15Oct 18Oct 21Oct 26
28°FOct 9Oct 14Oct 17Oct 20Oct 22Oct 25Oct 28Oct 31Nov 4
24°FOct 19Oct 23Oct 27Oct 29Nov 1Nov 3Nov 5Nov 9Nov 15
20°FOct 29Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 19Nov 24
16°FNov 5Nov 8Nov 11Nov 15Nov 17Nov 20Nov 24Nov 28Dec 2

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°F168162157154150147143139133
32°F188182177173169165162156150
28°F208201197193190186182177169
24°F227221215211207203200195188
20°F246238233229225221217213206
16°F265256251246242238234229223

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
7,063
Cooling degree days, base 65°F
777
Growing degree days, base 40°F
5,049
Growing degree days, base 45°F
3,961
Growing degree days, base 50°F
2,989
Growing degree days, base 55°F
2,134
Growing degree days, base 60°F
1,394

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,47100
February1,22801
March948118
April514389
May20847321
June20177607
July5256716
August10198652
September11184428
October43611143
November852015
December1,26000

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 14.8 km from Fairbank. 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 USC00136199 (Oelwein 1E). Public domain.