Hatsukaichi experiences a temperate climate with significant seasonal variations. Winters are cool and sometimes harsh, with temperatures often below freezing in January and December, but also occasionally mild with highs reaching up to 17°C/63°F. Spring brings gentle warming, with temperatures gradually rising from around 2-26°C (36-79°F) in April and May. Summers are warm and humid, with high temperatures frequently above 30°C (86°F), while autumns are mild with temperatures dropping back down into the single digits and teens, similar to winters.