Grayslake, IL Weather & Climate Normals
Grayslake's real weather, in one number
Grayslake, IL scores 43/100 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.
Grayslake's hottest and coldest months
Grayslake's hottest month is Jul, averaging 72°F; its coldest is Jan, averaging 21°F, a 51°F swing across the year, one of the widest gaps in this dataset.
Rain and snow in Grayslake
Grayslake averages 38.45in of precipitation a year across roughly 128 days with measurable rain or snow, and 43.1in of snow a year.
Where Grayslake ranks
Grayslake ranks 4006 of 4876 US cities in this dataset for comfort score, and 244 of 330 within IL. About 21,262 people live there.
If you need tomorrow's forecast, not the 30-year average
Everything above is a 30-year average from MUNDELEIN 4 WSW, IL US, 6.3 miles from Grayslake, 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