May in Lillestrøm averages a daily high of 16.8°C with nights around 5.6°C. Expect roughly 12.9 wet days totalling 73.7mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Lillestrøm is June–August.
Based on SKEDSMO HELLERUD, NO (4.6km), 1995–2024. 12 years of May data.