Koriyama's winters are chilly, with temperatures often dropping below freezing and averaging around 1°C in January. Spring arrives in March, bringing rapidly warming temperatures that can fluctuate between -5°C and 25°C, with an average of 8°C. Summer is warm to hot, with July being the hottest month, averaging 24°C, while August's heat often reaches highs over 35°C. Autumn brings a return to milder temperatures, ranging from around 2°C in October to 11°C in November, before winter sets back in.