May in Elgin averages a daily high of 21.3°C with nights around 9.1°C. Expect roughly 13.8 wet days totalling 133.2mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Elgin is August–September.
Based on ELGIN WATER, IL US (2.9km), 1995–2024. 30 years of May data.