Irving Park climate

Irving Park Frost Dates and Growing Season

NOAA 1991-2020 normals for Chicago Ohare Intl AP, 17 km from Irving Park, elevation 658 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Chicago Ohare Intl 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 16 and the first fall freeze around October 28, a growing season of about 193 days.

Median at 36°F
last April 29, first October 18
Median at 32°F
last April 16, first October 28
Median at 28°F
last April 5, first November 7

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 13May 8May 4May 1Apr 29Apr 26Apr 23Apr 20Apr 15
32°FMay 1Apr 26Apr 22Apr 19Apr 16Apr 14Apr 11Apr 8Apr 3
28°FApr 19Apr 14Apr 10Apr 7Apr 5Apr 2Mar 31Mar 27Mar 21
24°FApr 8Apr 3Mar 31Mar 28Mar 24Mar 21Mar 17Mar 13Mar 7
20°FMar 29Mar 24Mar 20Mar 16Mar 13Mar 10Mar 6Mar 2Feb 26
16°FMar 19Mar 15Mar 11Mar 8Mar 5Mar 2Feb 28Feb 24Feb 17

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

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°F189183178174170167163158151
32°F213206201197193189185180173
28°F238231225221217212209204198
24°F260253247242238234229224217
20°F281273267262258254249244236
16°F299291284280275270266261253

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
5,974
Cooling degree days, base 65°F
1,003
Growing degree days, base 40°F
5,548
Growing degree days, base 45°F
4,369
Growing degree days, base 50°F
3,331
Growing degree days, base 55°F
2,427
Growing degree days, base 60°F
1,649

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,23401
February1,01503
March808230
April4688105
May19860338
June31199618
July2326789
August4277738
September77116491
October35515185
November713032
December1,06903

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 17 km from Irving Park. 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 USW00094846 (Chicago Ohare Intl AP). Public domain.