Shabbona climate

Shabbona Frost Dates and Growing Season

NOAA 1991-2020 normals for Shabbona 5 Nne, 8.6 km from Shabbona, elevation 861 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Shabbona 5 Nne. 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 28 and the first fall freeze around October 10, a growing season of about 163 days.

Median at 36°F
last May 8, first September 30
Median at 32°F
last April 28, first October 10
Median at 28°F
last April 17, first October 21

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

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

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°F163157151147144140136132125
32°F183177172167163159154149143
28°F204197192187184180175170163
24°F232223217212207204199193184
20°F256249244239235229225219212
16°F276268263257253249245240233

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
6,830
Cooling degree days, base 65°F
594
Growing degree days, base 40°F
4,768
Growing degree days, base 45°F
3,675
Growing degree days, base 50°F
2,709
Growing degree days, base 55°F
1,871
Growing degree days, base 60°F
1,154

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,36800
February1,12801
March892121
April519281
May22342301
June35144560
July12198651
August24142583
September13859376
October4608121
November827013
December1,20301

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 8.6 km from Shabbona. 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 USW00054811 (Shabbona 5 Nne). Public domain.