September in Hoorn averages a daily high of 19.3°C with nights around 10.7°C. Expect roughly 13.4 wet days totalling 81.8mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Hoorn is June–September.
Based on BERKHOUT, NL (5.5km), 1995–2024. 26 years of September data.