Historical weather data, all-time temperature records, and monthly climate averages for Waukegan, IL. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th in Waukegan sits right on the edge of winter's last stand — the average high is just 49° with a low that still dips to freezing. Across 82 years of records, the date has swung wildly, from a balmy 75° in 1997 to a brutal 12° low back in 1982. There's about a 4-in-10 chance you'll see some precipitation today, though actual snow is unlikely at just 3%.
Waukegan's weather has some teeth. The all-time high of 105° hit on July 4, 2012, while the coldest recorded temperature plunged to -31° on January 16, 1982 — a 136-degree spread that tells you everything about life on the southwestern shore of Lake Michigan. Single-day extremes round out the picture: 5.66 inches of rain on October 21, 1965, and a punishing 16.8 inches of snow on February 2, 2011.
Waukegan follows a classic Upper Midwest pattern: cold winters, warm summers, and not much in between. The coolest stretch runs mid-January, when average highs barely reach 29°, while the warmest weeks of the year arrive around July 16–22 with highs near 81° — which is also when the area sees its heaviest rainfall, averaging over an inch that week. If you're planning a visit, late spring and early fall offer milder temperatures, though you'll want to wait until May before expecting anything reliably above 60°.