- Seoul’s December normals are an average of 0.2°C, highs of 4.2°C and lows of −3.4°C (KMA, 1991–2020). That is a sharp drop from November’s 7.5°C average, and by late December it feels like January (average −2.0°C). On December 26, 2021, Seoul hit −15.5°C.
- Rain and snow are scarce: 22.6 mm of precipitation for the month, 6.4 snow days and 162.9 hours of sunshine. December in Seoul is bright, dry and cold. The average first snow falls on November 20, so December flurries are nothing unusual.
- Sunrise is 7:47 am and sunset 5:23 pm at the end of December in Seoul; it is dark by 5. Wear three layers, a thermal base, a mid-layer and a windproof shell, and plan to shed them indoors, where ondol floor heating runs hot. December 1 to March 31 is the fine-dust seasonal management period, so pack a mask or two.
Who this is for
- You are heading to Seoul in December and have not settled on what to wear
- You want the actual numbers on snow, rain and cold rather than guesses
- You want to know how to plan a day around short daylight and cold-wave days
The most common December mistake we see is packing for the winter you know at home. Seoul’s December averages 0.2°C, colder than a typical January in Tokyo, and a dry wind pushes the feel of it lower still.
The good news: it barely rains. December brings 22.6 mm of precipitation and 162.9 hours of sunshine, so clear skies are the norm. This is a gloves-not-umbrella month.
The other thing to know is that indoors runs hot. Korean buildings come standard with ondol floor heating, and cafes and subway cars are toasty. It is −3°C outside and 25°C inside, and your outfit has to absorb that swing by coming apart in layers.
This guide reads December through KMA’s normals, period by period, then covers the three-layer outfit, how to plan around a 5:23 pm sunset, dry air and fine dust, and a packing list. Cold is something preparation can cancel out!
Autumn’s Tail in Early December, Deep Winter by the End! Reading Seoul’s December Through the Normals
✔ Average 0.2°C, lows of −3.4°C, a 7°C drop from November
KMA’s 1991–2020 normals put Seoul’s December at an average of 0.2°C, with highs of 4.2°C and lows of −3.4°C. That is more than 7°C below November (average 7.5°C, highs 11.9°C, lows 3.5°C), and January goes colder still at an average of −2.0°C. The accurate way to think about December is early month as the end of November, late month as the start of January.
In practice, early December runs 5 to 8°C in the daytime; by the last third, daytime highs hover around 0°C and mornings below −5°C are routine. Extreme years happen: Seoul recorded −15.5°C on December 26, 2021. When the forecast shows the word “한파” (cold wave), that is the day to restructure around indoor plans.
Snow falls on 6.4 days a month on average. With the mean first snow on November 20, December flurries are ordinary. Snow heavy enough to stop traffic is rare, though; the real problem is ice on the pavement the next morning. Grippy soles are for the ice, not the snow.
| Month | Mean / high / low (°C) | Precipitation and notes |
|---|---|---|
| November | 7.5 / 11.9 / 3.5 | 51.1 mm. Mean first snow November 20 |
| December | 0.2 / 4.2 / −3.4 | 22.6 mm, 6.4 snow days, 162.9 sunshine hours |
| January | −2.0 / 2.1 / −5.5 | 16.8 mm. The coldest month of the year |
| Daylight, end of December | Sunrise 7:47, sunset 17:23 | Korea Astronomy and Space Science Institute (2025-12-31 / 2026-01-01) |
| Fine-dust seasonal management | December 1 to March 31 | Every winter. Seventh round: December 2025 to March 2026 |
✔ Decide your cold-wave escape route in advance On a −5°C day, a jjimjilbang keeps you for half a day. The 『jjimjilbang guide』 explains the naked-zone and pajama-zone split and the 16,000-won overnight rate, which fills a December backup day on its own.
Gloves Over Umbrellas! Three Layers for a Dry Cold of 22.6 mm and 162.9 Sunshine Hours
✔ Thermal base, thin down or fleece in the middle, windproof shell on top
With 22.6 mm of precipitation and 162.9 hours of sunshine, roughly two-thirds of December is clear. Windproofing matters more than waterproofing, and the outfit is three layers: a thermal base, a mid-layer (thin down, fleece or knit) and a windproof outer. What Koreans actually wear in December is the below-the-knee “롱패딩” (long padded coat), and it is the most rational answer.
The reason for three layers is the indoor heat. Subway cars, cafes and department stores run ondol and heating hard, and you will cross from −3°C outside to 25°C inside many times a day. Tune the mid-layer so you are comfortable with the coat off, and you stop sweating every time you enter a shop.
Extremities take a three-piece set: touchscreen gloves, a knit hat or earmuffs that cover your ears, and a scarf. Seoul’s wind is dry, and along the river or on the big avenues it takes 5°C off the feel. On your feet, thick socks and soles that grip ice. Heels and thin sneakers do not belong on December pavement.
The Sun Sets at 5:23 pm! Short Days, Dry Air and Fine Dust
✔ Sunrise 7:47 am, sunset 5:23 pm. Move evening plans earlier
At the end of December, Seoul’s sun rises at 7:47 am and sets at 5:23 pm (Korea Astronomy and Space Science Institute figures for December 31, 2025 and January 1, 2026). It is fully dark by 5. Do outdoor sights like Gyeongbokgung and Bukchon before 3 pm, then shift to lit-up districts like Myeongdong and Dongdaemun for the evening. That is the shape of a December day.
The air is dry too. With only 22.6 mm of precipitation and heating pulling indoor humidity down, lip balm and hand cream are essentials. In your hotel room, a damp towel hung up overnight makes a difference to your throat.
One note on air quality. Every year, December 1 to March 31 is Korea’s fine-dust seasonal management period, because winter is when PM2.5 tends to climb; the seventh round ran December 2025 to March 2026. It is not bad every day, but keep a mask in your bag for days when the weather app says “나쁨” (bad).
Escape Indoors on the Cold Days! December-Only Experiences, and How to Read the Weather App
✔ Jjimjilbang, cafes, underground malls: Seoul can fill a whole day indoors
Seoul has plenty of places that turn cold into fun. A jjimjilbang (Korean sauna) costs around 14,000 won for a daytime session and keeps you for half a day, and it feels best on a −5°C day. The underground malls at Gangnam Station and Express Bus Terminal, and indoor complexes like COEX and Lotte World, are your escape routes on cold-wave days.
There are December-only outdoor experiences too. The Seoul Plaza ice rink ran December 19 to February 8 last season (2025–26), skating in front of City Hall as a winter fixture. Seoul Winter Festa, which includes the Cheonggyecheon lantern festival, ran December 12 to January 4 last time. Dates for 2026–27 are usually announced in late November, so check before you fly.
For weather, the KMA app or your own weather app set to Seoul is enough. Watch three things: the morning low (−10°C or below means cold-wave territory), wind speed (5 m/s or more knocks the feel down hard), and the fine-dust grade (“나쁨” means mask). Check those three the night before and choose tomorrow’s outfit and destination. That is the December habit.
The Packing List, and Nothing Else! Seoul December Essentials and a Quick-Reference Table
To recap: December in Seoul averages 0.2°C, is sunny and dry, and goes dark at 5. Pack the following, and if in doubt prioritize the windproof coat and gloves. Normals are KMA 1991–2020; sunrise and sunset are Korea Astronomy and Space Science Institute figures.
- Clothes: thermal top and bottom, a mid-layer (thin down or fleece), a windproof coat (knee-length if possible), thick socks, shoes with grip
- Accessories: touchscreen gloves, a hat that covers your ears, a scarf, disposable hand warmers (convenience stores sell them locally)
- Dry air: lip balm, hand cream, throat lozenges
- Air quality: a few masks for “나쁨” fine-dust days
- Indoors: one layer that is comfortable on its own once the coat comes off. That is your ondol strategy
FAQ
How cold is Seoul in December?
The normals are an average of 0.2°C, highs of 4.2°C and lows of −3.4°C. Early December runs 5 to 8°C in the daytime; late December hovers around 0°C by day with mornings below −5°C. Seoul recorded −15.5°C on December 26, 2021.
Does it snow?
On average, snow is observed on 6.4 days in December. The mean first snow is November 20, so December snow is normal, but precipitation is only 22.6 mm for the month and most days are clear.
What should I wear?
Three layers: a thermal base, a mid-layer (thin down or fleece) and a windproof coat. Indoors runs hot with ondol heating, so tune the layers to be comfortable with the coat off. Gloves, a hat, a scarf and shoes with grip are also needed.
What time does it get dark?
At the end of December, Seoul’s sunrise is 7:47 am and sunset 5:23 pm. Finish outdoor sights by 3 pm and move to lit-up districts for the evening.
Do I need a mask?
December 1 to March 31 is the fine-dust seasonal management period, and some days see elevated levels. It is not every day, so carry a few masks for days when the weather app shows “나쁨” (bad).
- KMA climate normals (1991–2020), Open MET Data Portal
- KMA regional climate characteristics (Seoul mean first snow, first ice, first frost)
- Sunset on December 31, 2025 and sunrise on January 1, 2026 (Korea Astronomy and Space Science Institute, 2025-12-24)
- Seoul sunset 5:23 pm on December 31, sunrise 7:47 am on January 1 (Hankook Ilbo, 2025-12-24)
- Fine-dust seasonal management period (Seoul air quality information)
How this was checked: Korea Meteorological Administration climate normals (1991–2020), the Korea Astronomy and Space Science Institute’s sunrise and sunset release, and the Seoul city page on the fine-dust seasonal management period were verified online (2026-09-17). Temperatures are 30-year normals and vary year to year.