December in Berwyn averages a daily high of 3.4°C with nights around -3.6°C. Expect roughly 9.4 wet days totalling 49.2mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Berwyn is May–June.
Based on CHICAGO MIDWAY AIRPORT, IL US (8km), 1995–2024. 28 years of December data.