Oak Brook, IL Weather & Climate Normals
Oak Brook's real weather, in one number
Oak Brook, IL scores 45/100 on this site's reading of NOAA's own 30-year normals: strongly seasonal. Comfortable weather is limited to a shorter window; summers, winters, or precipitation swing wide. 5 of the year's 12 months average between 55 and 75°F, the range this site counts as mild.
Oak Brook's hottest and coldest months
Oak Brook's hottest month is Jul, averaging 74°F; its coldest is Jan, averaging 25°F, a 49.5°F swing across the year, one of the widest gaps in this dataset.
Rain and snow in Oak Brook
Oak Brook averages 39.9in of precipitation a year across roughly 116 days with measurable rain or snow, and 24.3in of snow a year.
Where Oak Brook ranks
Oak Brook ranks 3534 of 4876 US cities in this dataset for comfort score, and 152 of 330 within IL. About 8,188 people live there.
If you need tomorrow's forecast, not the 30-year average
Everything above is a 30-year average from WHEATON 3 SE, IL US, 6.4 miles from Oak Brook, not a prediction for any specific day.
More on how this is worked out
How the comfort score is calculated · Why some cities show no snow or rain figure