Seoul Weather by Month and What to Pack: Pack by Month, Not by Season

Seoul swings from a January average of −2°C to an August average of 26°C. March and May call for completely different clothes even though both are "spring", and July's rainfall peaks hard enough to change your itinerary, not just your bag. Here it is broken down by month.

Last checked: 2026-09-22·Desk-researched — not yet verified on site

1. 1Spring (Mar–May): fine dust matters more than layers

   March averages 6°C and still wants a winter coat; April hits 13°C and May 18°C. For cherry blossoms, the Korea Tourism Organization's 2026 forecast had Seoul opening on 3 April with full bloom around 10 April, peak falling roughly a week after first bloom — the dates shift by several days each year and the actual bloom can miss the forecast, so check that season's forecast rather than booking against a fixed window. Yeouido Spring Flower Festival and the Seokchon Lake Cherry Blossom Festival both opened on 3 April 2026. The real issue is yellow dust and fine particulates — March to May is the worst stretch of the year. Bring KF94 masks and check the air quality each morning.

2. 2Summer (Jun–Aug): the rainy season and humidity

   Under the Korea Meteorological Administration's 1991–2020 normals, the jangma rainy season in the central region that includes Seoul runs 25 June to 26 July — about 31.5 days. Jeju starts earlier, on 19 June, so the widely repeated "mid-June" date is not Seoul's. July's normal rainfall of 414mm is the wettest month of the year. August averages 26°C but the humidity makes it feel far hotter. A folding umbrella is essential — though convenience stores sell them for ₩3,000–5,000, so don't pack one. Indoor air conditioning runs cold, so bring one light layer.

3. 3Autumn (Sep–Nov): the best window

   22°C in September, 15°C in October, 8°C in November. Humidity drops and clear days are common — the best walking weather of the year. The Korea Tourism Organization's 2026 forecast puts foliage on Bukhansan in Seoul starting 23 October and peaking 4 November; the date moves every year, so check that season's forecast rather than booking against a fixed window. Typhoons are still possible into early September, so leave slack around your flights.

4. 4Winter (Dec–Feb): wind, not snow

   January averages −2°C and the wind makes it feel colder. Precipitation is actually low (about 17mm in January), so heavy snow is rare. Indoor heating runs hot, so thin layers plus a windproof outer shell beat one thick sweater. Thermal base layers, gloves and a hat that covers your ears do the most work.

5. 5What to pack regardless of season

   A 220V European-style (Type C/F) plug adapter, a power bank, and shoes you can walk in — Seoul days run well over 10,000 steps and subway transfers involve a lot of stairs. Bring only the medication you personally take; skincare, sheet masks, umbrellas and socks are all far cheaper here, so leaving suitcase space pays off.