Seoul Weather by Date: What It Was Actually Like
One thing to know up front. Seoul on the same date can swing more than 10°C from one year to the next. That is why “March? Bring a cardigan” advice keeps failing people.
The tool below works differently. Enter your dates and it pulls real recorded temperatures for every year from 2020 through 2025. Not an average — the actual numbers.
Look up your travel dates
Unit: °C · Open-Meteo ERA5 reanalysis data (reanalysis may differ slightly from observed values and wind chill)
| Date | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|
Data is for Seoul, 2020–2025. This is historical data, not a forecast — check the Korea Meteorological Administration short-term forecast right before your trip.
Why monthly averages fail
“Seoul in March: average 8°C.” That number is nearly useless. The same March can hit a daytime high of 20°C one year and 5°C another.
The shoulder seasons (March–April, October–November) are where this bites hardest. Two mistakes travelers make over and over:
- Dressing too light and buying clothes on day one — now you have more to carry.
- Dressing too heavy and hauling a coat around all afternoon — dead weight from noon onward.
Use the tool above. Pack for the coldest year in your range. Assume you will shed layers during the day. That is the safest formula.
Season by season — what to bring, what becomes a burden
| Period | What to wear | What turns into dead weight |
|---|---|---|
| Dec–Feb (winter) | Padded coat + thermals + knit, gloves, scarf | Your coat. Indoor heating is so strong you will carry it all day |
| Mar–Apr (spring) | Layers. Day–night gap can exceed 10°C | The jacket you shed by noon |
| May–early Jun | T-shirt + light outer layer | Almost nothing — the easiest season |
| Late Jun–Jul (monsoon) | Waterproof shoes, folding umbrella | Wet umbrella and damp outer layers |
| Jul–Aug (midsummer) | Light clothing, one thin layer for AC | Nothing really — but the heat itself is a burden |
| Sep–Oct (autumn) | Layers | The jacket you shed by noon |
| Nov | Coat or heavy jacket | Your coat |
How weather changes your luggage strategy
This is the part other weather guides skip.
Winter — storing your coat is a real option
Seoul indoors are intensely heated. Step into a café, a restaurant, or an underground shopping arcade and your padded coat becomes instant dead weight. On your last day, when you have checked out and have hours until an evening flight:
- Store your luggage in Hongdae — and put your coat in with it.
- Explore light, then grab everything right before heading to the airport.
This only works for indoor-heavy days. If you plan to walk outside for hours, keep the coat.
Heads-up: Winter means bulky bags, which means large lockers disappear fast. A staffed counter with a reservation is the safer call.
Summer — what not to put in a locker
Summer 2026 was especially brutal. On July 31, Yangsan (Gyeongnam) hit 41.4°C — a new all-time daily high for South Korea. Outdoor lockers get even hotter inside than the air outside.
Do not put these in a locker:
- Chocolate, macarons — anything that melts
- Lip balms, cream cosmetics, film
- Temperature-sensitive medication
Underground storage solves most of this. Hongik Univ. Station has multiple storage spots connected underground — summer, winter, and rainy days all favor these. → Hongdae Station Exit Guide
Monsoon and rain — staying dry door to door
Late June through July is monsoon season. It rarely rains all day — instead, it dumps suddenly.
- Dragging a suitcase through rain soaks both your bag and your clothes.
- Underground-connected storage lets you drop bags without stepping outside.
- Stowing a wet umbrella and damp jacket inside a sealed locker is a bad idea — they will not dry, and the smell lingers.
Why this matters most on your last day
You check your departure-day temperature for one reason: what you wear onto the plane.
- Seoul at 30°C, your destination at 10°C? Keep a jacket at the top of your suitcase — or in your hands.
- Seoul below freezing, your destination warm? You need room to stuff that padded coat at the airport.
If you plan to store your bags and spend a half-day in Hongdae, pack the clothes you will need right after pickup at the very top. That way you do not open your suitcase on the storage-counter floor and start digging.
Bottom line
- Check real dates, not monthly averages. The same date can swing 10°C or more across years.
- Pack for the coldest year in the range and you rarely go wrong.
- Shoulder-season jackets and winter coats are the real luggage problem. Consider storing them.
- In summer, keep meltables and medication out of lockers. Underground storage is your friend.
- Right before your trip, check the actual forecast. This tool is historical data, not a prediction.
checked: 2026-08-02 · Temperature data 2020–2025 (Open-Meteo ERA5)