Koshizuka experiences a gradual warming trend throughout the year, with temperatures fluctuating significantly between seasons. In winter, January and December are the coldest months, with average temperatures ranging from 6°C to 7°C, while February is slightly warmer. Spring brings rapid temperature increases, reaching an average of 15°C in April and 19°C in May. Summer months, June to August, see a plateau in high temperatures, averaging around 26-27°C, before slowly decreasing towards autumn. Autumn temperatures are generally mild, with October and November averaging around 12°C and 19°C respectively.