Travel time: Year-round
Jeju Island, often called the "Hawaii of Korea," possesses a humid subtropical climate (Cfa) that differs significantly from mainland South Korea. Governed by its mid-latitude position and the influence of the surrounding East China Sea, the island enjoys milder winters but experiences much higher humidity and more frequent precipitation year-round.
Locals refer to Jeju as Samdado, the island of three abundances: wind, stones, and women. The weather is defined by the wind, which is nearly constant. Throughout history, the islanders have adapted to these gales by building low-slung houses with thatched roofs tied down by thick ropes and Constructing batdam (volcanic stone walls) to protect crops from being flattened by the salty sea breeze.
The 1,947-meter Hallasan Mountain sits at the center of the island, acting as a massive weather wall. This creates distinct microclimates between the north and south:
Spring is a transitional season where the island wakes up in a burst of yellow canola and pink cherry blossoms. The weather is generally pleasant and clear, though "yellow dust" (fine sand from the Gobi Desert) can occasionally affect air quality. Spring is also the season of unpredictable "flower-chilling cold" (kkotsam-chu-ui), sudden brief cold snaps that occur just as the blossoms appear.
Summer is dominated by the East Asian Monsoon (Jangma), typically starting in late June. This period brings heavy, tropical-style downpours and high humidity. By August, the heat peaks, often remaining above 30°C (86°F) with "tropical nights" (temperatures staying above 25°C). This is also the window for potential typhoons, which can bring intense wind and rain to the southern and eastern coasts.
Considered by many locals to be the best weather of the year, autumn is dry, crisp, and stable. The high humidity of summer evaporates, replaced by clear blue skies. It is the season of silver grass (eoksae) which sways across the island's volcanic cones (oreum).
Winter on Jeju is much warmer than in Seoul, with temperatures rarely dipping below freezing at the coast. However, the island's famous wind creates a significant wind-chill factor. While coastal snow is rare and usually melts quickly, the moisture-laden winds hitting Hallasan produce heavy snow in the highlands, creating a stunning contrast between the white peak and the green citrus orchards below.
Weather on Jeju is as much about sensation as it is about temperature. In summer, the air feels heavy and "muggy," making the sea breeze a vital relief. In winter, the temperature might read a mild 6°C (43°F), but the piercing northwest wind can make it feel like sub-zero conditions. Visitors should expect rapid changes; it is common to experience "Jeju's four seasons in a single day," where a sunny morning can turn into a misty, drizzling afternoon as clouds snag on the slopes of Hallasan.