Weather Seoul
Seoul is South Korea's capital city, located in northern South Korea near the border with North Korea. The city has a very rich history, one that Koreans are very proud of and show off in their numerous historical sites.
Mountains surround Seoul, the most notable being Bukhansan on the north side of the city. The Han River bisects Seoul, and though it has historic and cultural significance, does not affect the climate much. Other than the river and surrounding mountains, Seoul's topography features gently rolling hills.
Seoul's weather has extreme differences between summer and winter. Summer months are influenced by Seoul's proximity to the ocean and the Pacific typhoon season. Winters are influenced by the Siberian high-pressure systems, and northwesterly winds often bring bitter cold temperatures to Seoul.
Because of these extremes, most people choose to visit Seoul during the spring and autumn.
April and May have mild temperatures and humidity levels that most people will be comfortable with. These months strike a balance between clear skies, minimal precipitation, and favorable temperatures. The same can be said of late September to early November. Early September is still rainy and humid, and temperatures quickly drop by mid November.
The weather in Seoul is comparable to Beijing, China, with the hot humid summers, cold dry winters, and short but heavy monsoon season. Seoul thankfully does not see as many typhoons as other countries in East Asia.
Summer Weather in Seoul
Summer starts in early May in Seoul and typically ends in September. The temperatures are quite warm, with daytime temperatures of 22°C in May, 28°C in August, and cooling to 24°C in September. Nights still reach 20°C in July and August.
Summers are also uncomfortably humid in Seoul, as moist warm air moves in from the ocean. When this air mass collides with the dry air of central Korea, heavy monsoons develop, drenching the area in rain. The monsoon season is rather short, typically lasting from late June to August, but massive amounts of rain fall in this short period. Monthly averages close in on almost 400mm of rain, with over a 50% chance of precipitation every day.
Most visitors spend their time indoors when visiting Seoul in the summer. Uncomfortably high humidity, high temperatures, and wet weather prevent many enjoyable outdoor activities. Despite the long days, there are only four to five hours of sunshine every day.
Extreme Weather
Typhoons do affect Korea but not regularly. The Pacific typhoon season lasts from July through September, and during this time Korea is usually affected by only one or two typhoons. High winds often don't pose a problem for Seoul, but the torrential rains can cause severe flash flooding.
Seoul has also been having some catastrophic heat waves, and in 2016 there were a number of agricultural and health emergencies as daytime temperatures regularly hit the mid-30s. Summer record highs have been recorded at 38°C.
Autumn Weather in Seoul
The transition to autumn usually happens around October. During this time the temperature, humidity, and rainfall will drastically drop. September rains average 169mm, but by October only 52mm of rain falls. By the end of the month the average daytime temperature falls to 16°C, from 23°C in the beginning of the month. The monsoon season has been over for a month and typhoons are rare.
The clear skies, cooler temperatures, and lack of rain make autumn in Seoul very enjoyable. There are a number of parks and gardens with wonderful displays of autumn colors. The Secret Garden at Changdeokgung Palace is especially pleasant.
Winter Weather in Seoul
By the time winter arrives in November, much colder air settles in over Seoul thanks to the cold air masses moving down from Siberia. This air is also very dry, and the contrast between Seoul's wet summers and dry winters is drastic. Winter months typically only get 20mm of rain. Every now and then precipitation will fall in the form of snow, but for the most part winters are characterized by bitter frosty air.
January is the coldest month in Seoul, with nighttime averages of -9°C. Daytime temperatures barely eek above freezing, with an average of 1°C. The coldest temperature ever recorded in Seoul was -23.1°C.
Because of the high pressure that sits over the Korean peninsula, winters are typically very clear with bright blue skies. This is a great change from cloudy, rainy summers. Even with the shorter days, you'll still get an average of five hours of sunshine every day throughout the winter. The winds, however, can make the air feel much colder.
Despite the cold weather, winter does make Seoul a great base for those who enjoy snow sports. While Seoul doesn't have any ski resorts near the city, there are a number of small resorts within a couple of hours.
Spring Weather in Seoul
Spring is probably the most popular season for tourism in Seoul, and you might be able to find some great travel deals.
Unlike autumn, there is no residual precipitation from the preceding season. Average rainfall amounts average around 100mm during the seasonal transition.
You also still have the clear skies that dominated winter. However, the air temperature is much more comfortable than winter. The average temperature in April is an impressive 13° warmer than February, averaging 17°C. Nights are still cool at 5°C, but in May the nights will warm up to 11°C.
The lack of any extreme weather makes spring a beautiful season. Many locals and tourists are able to take to the outdoors and enjoy the magnificence that surrounds Seoul. One of the activities that defines Seoul in the spring is the infamous Cherry Blossom Festival. Many of Seoul's other gardens and parks explode in color during the spring.