Hinckley climate

Hinckley Frost Dates and Growing Season

NOAA 1991-2020 normals for Chicago Aurora Muni AP, 13.2 km from Hinckley, elevation 710 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Chicago Aurora Muni AP. 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 13, a growing season of about 166 days.

Median at 36°F
last May 6, first October 2
Median at 32°F
last April 28, first October 13
Median at 28°F
last April 18, first October 23

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 17May 13May 9May 6May 4May 1Apr 28Apr 24
32°FMay 11May 7May 4May 1Apr 28Apr 25Apr 22Apr 18Apr 14
28°FMay 4Apr 28Apr 24Apr 21Apr 18Apr 15Apr 12Apr 9Apr 3
24°FApr 24Apr 19Apr 15Apr 10Apr 6Apr 3Mar 31Mar 24Mar 19
20°FApr 13Apr 4Mar 31Mar 29Mar 24Mar 20Mar 17Mar 12Mar 5
16°FMar 30Mar 24Mar 19Mar 16Mar 13Mar 10Mar 6Mar 2Feb 25

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

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°F166160154150147143139134126
32°F185179174170166163158152145
28°F207200195191187183178173163
24°F231223218213209205201195188
20°F257249242237232228223218211
16°F277269263258254250245239231

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
6,433
Cooling degree days, base 65°F
781
Growing degree days, base 40°F
5,144
Growing degree days, base 45°F
4,014
Growing degree days, base 50°F
3,013
Growing degree days, base 55°F
2,138
Growing degree days, base 60°F
1,388

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,31400
February1,07902
March845125
April491597
May19756336
June29177599
July6257716
August12193646
September11380421
October41611150
November791018
December1,14103

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 13.2 km from Hinckley. 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 USW00004808 (Chicago Aurora Muni AP). Public domain.