Niihama's winters are cool and variable, with temperatures often below freezing in January and February, but also experiencing milder days. As spring arrives, temperatures gradually warm up, with April and May seeing increasingly pleasant conditions. Summer is hot and humid, with July and August being the peak months for high temperatures. Autumn brings a welcome respite from the heat, with September still warm but October cooling down again. The cold returns in November and December, although not as severe as in winter.