Oak Lawn, Illinois, United States

Frost dates for Oak Lawn

The full distribution rather than a single date. Every figure below is a percentile of 30 years of daily minimum temperatures at this location, expressed as the date it fell on.

Median last spring frost

22 April

Half of years are later than this. Not a planting date.

Median first autumn frost

31 October

The far end of the outdoor season.

Frost-free season

192 days

Between those two dates in a median year.

Last and first frost by severity

Read a row as: in this fraction of years, the last frost of spring had already happened by this date. The 90% column is the cautious planting date; the 10% column is the gamble.

Light frost — nights at or below 0°C (32°F). Air temperature reaches freezing. Kills basil, beans and unhardened tomatoes; hardy crops shrug it off.
Frost 1 year in 10 Median 9 years in 10 Earliest Latest
Last of spring 10 Apr 22 Apr 5 May 7 Apr 21 May
First of autumn 12 Oct 31 Oct 9 Nov 8 Oct 22 Nov
Frost-free days 213 192 160 every year on record saw this
Moderate frost — nights at or below -2.2°C (28°F). Damages half-hardy plants and most blossom. This is the threshold that decides a fruit crop.
Frost 1 year in 10 Median 9 years in 10 Earliest Latest
Last of spring 24 Mar 5 Apr 16 Apr 11 Mar 10 May
First of autumn 30 Oct 7 Nov 23 Nov 21 Oct 9 Dec
Frost-free days 244 217 197 every year on record saw this
Hard frost — nights at or below -4.4°C (24.1°F). Ground freezes and even hardy crops check their growth. Effectively the end of the outdoor year.
Frost 1 year in 10 Median 9 years in 10 Earliest Latest
Last of spring 6 Mar 23 Mar 5 Apr 26 Feb 8 Apr
First of autumn 3 Nov 18 Nov 8 Dec 31 Oct 23 Dec
Frost-free days 277 240 212 every year on record saw this

Dates in the southern hemisphere are computed on a growing year that starts in July, which is why "last of spring" falls where it should rather than in the middle of the calendar.

Chance of frost, week by week

Jan Mar Apr Jul Sep Oct Dec
Chance of at least one air frost during each week of the year, measured across the full record. The flat stretch in the middle is your frost-free season.

Temperature through the year

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Mean monthly temperature across the record. Months shown in blue average at least one air frost.

Monthly means and average number of frost nights.
Month Mean low Mean high Frost nights
January -7.8°C -0.4°C 28.4
February -6.5°C 2.1°C 25.9
March -1.6°C 8.2°C 21.5
April 3.4°C 14.6°C 6.7
May 9.4°C 20.4°C 0.2
June 15.2°C 25.7°C 0
July 18.1°C 28.1°C 0
August 17.8°C 28°C 0
September 13.7°C 24.7°C 0
October 7°C 17.5°C 1.4
November 0.5°C 9.2°C 14.8
December -4.7°C 2.5°C 25.9

Turn these dates into a planting calendar →

Nearby

Compare with places close by

Orland Park Zone 5b 12 km Last frost 25 Apr First 22 Oct Cicero Zone 7a 15 km Last frost 4 Apr First 17 Nov Tinley Park Zone 6a 15 km Last frost 22 Apr First 31 Oct Berwyn Zone 7a 16 km Last frost 4 Apr First 17 Nov Oak Park Zone 7a 19 km Last frost 4 Apr First 17 Nov Hammond Zone 6a 26 km Last frost 22 Apr First 31 Oct Bolingbrook Zone 5b 26 km Last frost 25 Apr First 22 Oct Naperville Zone 5b 33 km Last frost 26 Apr First 22 Oct

Seasonal context

Rainfall and the growing season in Oak Lawn

May has the highest average precipitation (114 mm); January has the lowest (51 mm). Compare this pattern with the planting windows and your water supply.

Jan 51 mm
Feb 53 mm
Mar 62 mm
Apr 92 mm
May 114 mm
Jun 105 mm
Jul 102 mm
Aug 105 mm
Sep 82 mm
Oct 92 mm
Nov 61 mm
Dec 58 mm

During wetter months, check that beds and containers drain after heavy rain. During drier months, plan how you will keep seeds and new transplants watered. Monthly averages can hide long dry spells and intense storms; they do not show soil moisture, humidity or this week's weather.

Source: NASA POWER, corrected MERRA-2 precipitation, 2001–2020. Values are approximate monthly totals, including the water equivalent of snow, from the nearest 0.5° × 0.625° grid cell. This reference period differs from the temperature record. Rainfall provides context and does not change the calculated planting dates. Method and limitations.

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