Winters in Muroran are cold and snowy, with temperatures often below freezing from January to February, averaging around -2°C. Spring brings a slow warming trend, with temperatures rising to an average of 8°C by April, but still experiencing occasional frosts. Summer is warm and sunny, with July and August being the hottest months, averaging around 22°C, while September sees a slight cooling trend. Autumn brings temperatures back down, similar to spring, but with more pronounced diurnal temperature variations. Frosts return in November, signaling the start of another cold winter.