Sanmu, Japan experiences a mild climate with temperatures gradually warming up in spring. March marks the beginning of warmer days, with temperatures ranging from 4-20°C, while April and May bring more consistent highs around 15-19°C. Summer months from June to August are warm and humid, with July being the hottest month at an average temperature of 25°C. Autumn brings a cooling trend, with September temperatures similar to March's, before dropping in November. Winters are generally mild, with January and December averaging around 7-9°C.