December in Arlington Heights averages a daily high of 2.9°C with nights around -4.7°C. Expect roughly 8.1 wet days totalling 44.5mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Arlington Heights is May–September.
Based on CHICAGO PALWAUKEE AIRPORT, IL US (7.2km), 1995–2024. 29 years of December data.