Shimonoseki is a year-round destination, but the seasons make a real difference.
Spring (March–May) is the finest time to visit. Cherry blossoms at Kozanji Temple in Chofu are exceptional — the pale pink flowers against dark cypress-bark rooflines are one of the most striking spring scenes in western Japan. Temperatures are mild (15–20°C) and the waterfront is pleasant for walking.
Summer (June–August) is hot and humid, with temperatures often topping 35°C. The Kanmon Strait hosts the Kanmon Sea Festival in August, and Bon Odori dancing takes place across the city. Worth seeing, but the heat can be draining.
Autumn (September–November) brings relief from the heat and some fine foliage around Chofu in October. The fugu season opens in October, so this is a good time to eat the city's signature dish at its peak.
Winter (December–February) is cool and occasionally wet, but fugu is at its best — the cold water makes the fish leaner and more flavourful. Crowds are minimal and prices are lower.
The Karato Sunday morning market runs year-round, though it is most atmospheric from October through April when fugu is in season.