May in Oshkosh averages a daily high of 19.6°C with nights around 9.1°C. Expect roughly 12.5 wet days totalling 106.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Oshkosh is May–September.
Based on OSHKOSH, WI US (1.3km), 1995–2024. 30 years of May data.