Kosai's winters are mild, with temperatures rarely dipping below freezing, while springs and autumns are characterized by gentle warming. Summer brings sweltering heat, with highs often reaching the mid-30s Celsius. In contrast, winter is cool but not harsh, with occasional chilly snaps in January and December. The warmest months are July and August, with temperatures rarely dropping below 20C at night, while September and October experience a gentle cooling trend. Cooler temperatures return by November, ushering in the mild winter conditions once more.