Ishikari's winters are harsh, with temperatures often dropping below -22°C in January and February, averaging around -5°C. Spring brings a gradual warming trend, with temperatures rising to averages of 7°C by April and 12°C by May. Summers are warm, with July being the hottest month, but temperatures rarely exceed 35°C. Autumn is mild, with temperatures dropping back down into the single digits by October. Winters return in December, with temperatures again dipping below -20°C.