Iwaki's winters are quite chilly, with temperatures often below freezing in January and February. As the seasons transition into spring, temperatures gradually warm up, reaching averages of around 12°C by April and 17°C by May. Summers are warm to hot, with July and August being the hottest months, but even then, nighttime temperatures can drop significantly. Autumn brings a return to cooler temperatures, with October averaging around 15°C before dropping again in November and December.