What’s the most important packing rule for Seoul?

Layering. Spring and fall can have a 10°C+ swing in one day. In summer, indoor air conditioning is icy — always carry a light cardigan. For winter, the standard is thermal + sweater + padded jacket (three layers).

Which months are the hottest and coldest in Seoul?

Based on recent 6 years (2020–2025), the hottest period is late July to early August, with highs up to 38°C. The coldest month is January, with lows dropping below –18°C. Use the calculator above to check real temperatures for your travel dates.

When is monsoon season and how much rain should I expect?

Seoul’s rainy season usually runs from late June to late July. Average July rainfall is about 300 mm (based on 2020–2025). Rain comes in sudden downpours rather than all-day drizzle. Pack a compact umbrella and waterproof shoes.

Seoul Weather Guide: What to Pack by Season & Real Temperature Data (2026)

The short answer Seoul has four distinct seasons, and temperatures can vary wildly within the same season. Summers (July–August) can hit 35°C, and winters (January) can drop to –18°C. The most reliable packing guide is to check what the weather actually was on those exact dates in recent years. Use the calculator below to look up your travel dates.

One of the trickiest things when planning a Seoul trip is figuring out what to pack. Most online advice just says “bring a cardigan in spring” — vague and not very helpful. This guide is based on real Seoul weather data from 2020 to 2025 (6 years), so you can see exactly what temperatures to expect on your travel dates, along with seasonal packing tips.

The golden rule for Seoul packing

Layer up. Spring and fall have temperature swings of 10°C+. Summer AC indoors is brutal — always have a light cardigan. Winter is three layers: thermal + sweater + padded jacket. Hottest (July–August) up to 35°C, coldest (January) down to –18°C.

🧮 Seoul Weather Comparison Calculator: What was it really like on your travel dates?

Pick your travel dates and see the daily high and low temperatures for each of the last 6 years. You can select up to 7 days.

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📡 Check the live forecast Naver Weather Naver Weather (detailed) KMA Short-term AccuWeather

Spring (March–May): A Season of Big Temperature Swings

Spring in Seoul is the most unpredictable season — from below freezing in early March to 25°C+ in late May. In March you still need a winter coat, but by mid-April a light jacket is enough.

Month	Avg Low (6 yrs)	Avg High (6 yrs)	Key Items
March	-1°C – 2°C	10°C – 14°C	Wool coat, sweater, scarf
April	3°C – 7°C	16°C – 20°C	Trench coat, cardigan, light sweater
May	9°C – 14°C	22°C – 27°C	T-shirt + cardigan, light shirt

Key tip: Even during cherry blossom season (April), mornings and evenings can dip below 5°C. Layer up — something light for the day, something warm for the evening.

Summer (June–August): Hot and Humid

Seoul summer is a combination of high heat + high humidity. The monsoon starts in late June, and from mid-July onward heatwaves push temperatures above 35°C.

Month	Avg Low (6 yrs)	Avg High (6 yrs)	Key Items
June	15°C – 19°C	25°C – 29°C	T-shirt, light long pants, compact umbrella
July	20°C – 24°C	28°C – 33°C	Breathable short sleeves/shorts, sun hat, umbrella
August	21°C – 25°C	29°C – 35°C	Linen/cotton, sandals, sunscreen essential

Key tip: If you only wear tank tops in summer, indoor air conditioning will freeze you. Always keep a thin cardigan or shirt in your bag. Also, heatwave warnings are common from late July to early August — avoid outdoor activities from 1–4 PM.

Fall (September–November): The Best Time to Visit

Fall is Seoul’s golden season. Early September still feels like summer (25°C+), but from mid-October the weather becomes crisp and clear. By November, nights drop below freezing.

Month	Avg Low (6 yrs)	Avg High (6 yrs)	Key Items
September	16°C – 20°C	25°C – 28°C	Summer extension, light longslee