Gronau's weather is marked by a gradual warming trend as the year progresses. Winters are chilly, with temperatures often below freezing, but occasional warmer days bring temperatures into double digits. Spring brings rapid temperature increases, with March and April averaging around 6°C. Summer months of June, July, and August enjoy warm to hot conditions, with average highs above 18°C, while September sees a slight drop in temperature. Autumn is characterized by mild temperatures, with October averaging 11°C, before the cold winter sets in once more.