January in Naperville averages a daily high of -0.5°C with nights around -9.1°C. Expect roughly 9.7 wet days totalling 48.7mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Naperville is August–September.
Based on AURORA WATER, IL US (13.4km), 1995–2024. 30 years of January data.