What jangma (장마) actually is
Korea's rainy season, known as jangma (장마), typically runs from late June through late July, according to the Korea Tourism Organization. It isn't a month of nonstop drizzle — it's a band of unsettled, humid weather that sits over the peninsula and produces heavy, sometimes intense bursts of rain interspersed with muggy, overcast stretches and the occasional clear day. Summer overall (June–August) is Korea's hottest and most humid stretch, and jangma overlaps with the start of it, so the sticky heat arrives at the same time as the rain rather than after it. Don't plan a trip around "it rains every day" — plan around "it can rain hard with little warning, and the air stays heavy even when it doesn't."
Typhoon season and what a warning means for you
The Korea Tourism Organization notes that the period from June through October also brings several typhoons to the region each year. Not every one makes landfall — many track close to the coast or brush past the south and Jeju before curving out to sea — but when a storm is forecast to hit, the practical effects show up fast:
- Jeju flights get grounded. This is the single most itinerary-relevant risk of the season — Jeju's flight schedule is the first thing disrupted when a typhoon approaches, and it can strand travelers on either end for a day or more.
- Ferries stop running, including routes to islands off the south coast and Jeju.
- Trails and cable cars close in the national parks (see below) until conditions clear.
- Outdoor attractions and riverside parks close as a precaution even before the worst of the weather arrives.
If your trip includes a Jeju leg or an island-hopping stretch during typhoon season, build in a buffer day rather than a tight connection, and check your airline's status the morning of.
Where to check current warnings
The Korea Meteorological Administration (KMA), at weather.go.kr, is the official source — it runs a dedicated typhoon-tracking section with current storm paths and a historical archive, plus a general forecast for every region. For phone-based Korean-language weather info, KMA's call center is 131.
For a broader disaster picture — not just weather but landslide, flood, and other hazard alerts in one place — check SafeKorea (안전신문고/국민재난안전포털) at safekorea.go.kr, the government's central disaster and safety portal. It aggregates warnings across categories including severe weather, flooding, and landslides, and is the home of Korea's nationwide emergency disaster text alert system, which pushes location-based alerts to phones in an affected area during a warning — a system you'll likely experience firsthand if you're in Korea when a typhoon or heavy-rain warning is issued, even as a foreign visitor on a Korean SIM or roaming plan.
For trail and park-specific closures, the Korea National Park Service (KNPS), at knps.or.kr, is the body that posts closure notices for national parks — relevant if your trip includes Seoraksan, Jirisan, Hallasan, or any other park trail, since sections are shut during and after heavy rain when landslide risk rises.
Worth saving before you travel: Korea's general emergency numbers are 112 (police) and 119 (fire and medical emergencies), and the 1330 Korea Travel Hotline (+82-2-1330) is a tourist-specific line staffed in multiple languages, including English, for anything from a cancelled ferry to a medical question — useful precisely because a typhoon disruption is the kind of situation where you want a human on the phone rather than a search engine.
Flash flooding and closures in Seoul
Heavy jangma or typhoon-linked downpours can cause flash flooding in Seoul's lower-lying areas, and the riverside Hangang parks — the paths, lawns, and cycling routes that line the river — are closed to the public when water levels rise, sometimes with very little notice. If you had a picnic or a bike ride planned along the river, have a plan B on any day with a heavy-rain warning in effect.
What to actually pack
- An umbrella, not just a rain jacket. Korean summer humidity means a rain jacket traps heat and sweat against your skin — you'll be just as wet from the inside. A sturdy umbrella (convenience stores sell cheap ones everywhere) handles sudden downpours without the sauna effect.
- Shoes you don't mind getting soaked. Waterproof hiking boots are overkill and stay wet for days in this humidity. Quick-drying sandals or shoes you can towel off are more practical for city walking.
- A dry bag or ziplock for electronics — sudden bursts mean your phone or camera can get caught out before you find cover.
- Something for the humidity itself, not just the rain — even on dry days in this window, high humidity means clothes take longer to dry and anything leather or suede is worth leaving at home; quick-dry synthetic fabrics hold up far better over a multi-day trip.
Indoor backup plans
Because bursts of rain are sudden rather than constant, the practical move is to build flexibility into each day rather than avoid the season entirely: museums, palaces' indoor exhibition halls, shopping districts (Myeong-dong, underground arcades near major stations), and department stores all make easy backup plans when a downpour hits mid-afternoon.
The upside of traveling in this season
Jangma and the shoulder weeks around it are genuinely the cheapest and least crowded time to visit Korea's major sights — palaces, trails, and popular photo spots that are packed in spring and autumn are noticeably emptier. The rain also means everything is green and the waterfalls are at their fullest, which is a real draw on Jeju in particular, where the island's waterfalls are at their most dramatic right after heavy rain.