May in Hammond averages a daily high of 21.3°C with nights around 9.9°C. Expect roughly 13.4 wet days totalling 123.3mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Hammond is August–September.
Based on PARK FOREST WATER, IL US (17.9km), 1995–2024. 29 years of May data.