October in Waterloo averages a daily high of 16.9°C with nights around 4°C. Expect roughly 8.4 wet days totalling 71mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Waterloo is August–September.
Based on WATERLOO MUNICIPAL AIRPORT, IA US (8.4km), 1995–2024. 30 years of October data.