The island’s climate is less extreme than that of the Korean peninsula, and the mild winters mean palm trees, cacti, orange orchards and even pineapple plants thrive. Despite this, don’t expect tropical temperatures, but rather a moderate but fickle, four-seasons-in-a-day climate, typical of islands.
Jejudo is also the rainiest place in Korea thanks to the country’s highest mountain, Hallasan (1950m). But while most of the nation gets up to 60% of its rainfall during the summer rainy season, Jejudo’s is more spread out. Downpours are least likely during autumn.
The island is noted for its strong winds, but they are usually brief. Conditions are often misty or hazy, except in autumn.
Hallasan is the dividing line between the subtropical oceanic southern side and the temperate north. Conditions on the peak can change rapidly, as it’s a cloud trap.
Despite the heavy rainfall, surface water is a rarity due to the island’s porous volcanic rock. The riverbeds are usually dry and the waterfalls are spring-fed. Underground water, by contrast, is abundant – Jejudo is basically one giant sponge.
Swimmers: being 33° north of the equator, you’ll want a wetsuit unless you’re swimming in July and August – or in a swimming pool.
View jeju.kma.go.kr for a detailed daily weather forecast in English.