Index


Introduction



The climate of the Republic of Korea is cold but sunny in winter, while it’s hot and sultry with abundant rainfall in summer. Spring and autumn are quite short but pleasant. The latitude of the country is not high: the border with North Korea is located on the 38th parallel, but winter is cold because of the prevailing winds from Siberia.
South Korea is affected by the Asian monsoon regime: in winter cold air masses from the Asian continent prevail, while in summer the country is reached by warm and moist air masses of tropical origin. For this reason, the precipitation pattern is opposite to that of the Mediterranean climate: the driest season is winter, while the rainiest one is summer. Moreover, in summer and in early autumn, South Korea can be affected by typhoons.
Total annual precipitation is significant, spanning generally from 1,200 to 1,500 millimeters (47 to 60 inches), with the exception of both the southern coast, where it is higher and can reach 1,700 mm (67 in), and the northernmost inland regions, where it is lower and can go down to 1,000 mm (40 in), in addition to some particularly sheltered valleys like that of Daegu (or Taegu), where it does not exceed 1,000 mm (40 in) per year.

Winter, from late November to mid-March, is freezing in the north and in the interior, while it’s milder, but still with night frosts, along the southern coast. The sun often shines. Snowfalls are relatively rare and not abundant. A cold and dry wind often blows from the continent, sometimes full of dust. Because of the greater exposure to cold winds of Siberian origin, at a given latitude winter is colder on the west coast than on the east coast. The average January temperature exceeds 0 degrees Celsius (32 °F) only on the southern coast, while on the east coast it's around freezing even in the north. The interior is obviously colder than the coastal areas, in fact, in the north-central inland area (see Chuncheon) the average temperature in January is around -4 °C (25 °F).
In the capital, Seoul, located near the coast but in the north-west, which as we mentioned is the region most exposed to cold winds, the average temperature in January is -2.5 °C (27.5 °F).
In the southernmost cities, such as Mokpo and Busan (or Pusan), the climate is much milder, and the average temperature in January goes up to around 3 °C (37.5 °F).
However, during cold spells, the temperature can drop to -20 °C (-4 °F) in Seoul and in northern inland areas, and around -10 °C (14 °F) in the south, while it only drops a few degrees below freezing on the island of Jeju.
The north-east is mountainous, and in addition to being cold, it is also quite snowy. This is the region (called Gangwon-do) where there is the largest number of ski lifts, which given the low temperature are also found at quite low altitudes, below 1,000 meters (3,300 feet). The highest mountain in the area is Seorak, 1,708 meters (5,604 feet), protected in a national park.
Not only the mountains, but also the northeast coast in winter is a bit wetter (although it is milder): in this season the average monthly precipitation along the north-east coast is about 45/60 mm (1.8/2.4 in), while in Seoul it is about 20/25 mm (0.8/1 in). The southwest coast, where Mokpo is located, and Jeju Island, are a bit more rainy and less sunny as well.
The least snowy area is the south-east coast because of the higher temperature, but also because in periods of bad weather the wind blows from the south. There are on average 25 days with snowfall (maybe light) per year in Seoul (as mentioned, located in the northwest), 22 days in Incheon (near Seoul but on the coast), 27 in Mokpo (on the south-west coast, which is a milder but also more humid area), 12 in Daegu (in the south-eastern inland areas), and only 5 in Busan, on the southeast coast.

Konjiam, ski lift near Seoul

Spring, from mid-March to May, is initially cool, and gradually becomes milder, but the rains become more frequent because of the formation of low pressure systems.
In winter, and especially in spring (March to May, which is called yellow dust season), South Korea (but especially the Seoul area) can be reached by the yellow dust (HwangSa in Korean) coming from the desert of Mongolia and from China; the dust forms a characteristic haze and can cause breathing problems and eye irritation.

Summer, from June to August, is hot, humid and rainy. The high humidity makes the heat sweltering, especially in July and August. Rainfall can be heavy especially in July and August. Two thirds of the annual rainfall occur in summer. However, between periods of bad weather, there can also be sunny days, which may be hot.
Especially between late June and early August, an almost stationary front (called Changma) moves over Korea, which can cause heavy rainfall (sometimes associated with floods) but also fog, low clouds and drizzle. In the second part of summer, it goes a bit better and the amount of sunshine increases, although typhoons can add more rain.
Being characterized by different periods of bad weather, summer is the least sunny season, at least if you consider the length of the day.

Autumn, from September to late November, is pleasant, especially in the month of October, when the maximum temperatures are around 20/22 °C (68/72 °F). In addition, in autumn it usually rains less than in spring.

Center-north



In the center-north, winter is very cold, in fact the average January temperature is equal to or less than 0 °C (32 °F). As mentioned, the coldest areas are those of the interior. On the other hand, summer is hot and muggy.
Here are the average temperatures of Chuncheon, which as mentioned is located in the northern inland area.
Chuncheon - Average temperatures
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)-8-605111621201571-5
Max (°C)031017232628282418102
Min (°F)182132415261706859453423
Max (°F)323750637379828275645036

Seoul

As mentioned, winter in Seoul is very cold, although it is quite sunny. On the other hand, summer is hot and muggy. Here are the average temperatures.
Seoul - Average temperatures
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)-6-4171318222217103-3
Max (°C)241018232729302620124
Min (°F)212534455564727263503727
Max (°F)363950647381848679685439

Here is the average precipitation in Seoul. As you can see, summer is clearly the rainiest season.
Seoul - Average precipitation
MonthJanFebMarAprMayJunJulAugSepOctNovDecYear
Prec.(mm)202545751001353303501405055251345
Prec.(in)0.811.833.95.31313.85.522.2153
Days767891016149797108

In Seoul, summer is the least sunny season because of the monsoon. Here are the sunshine hours per day.
Seoul - Sunshine
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Hours566776456655

Near Seoul, the Yellow Sea is very cold in winter, but it warms up a lot in summer, reaching 24 °C (75 °F) in August, when you can swim, as can be seen from the sea temperatures at Incheon.
Incheon - Sea temperature
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Temp (°C)5558131722242319149
Temp (°F)414141465563727573665748

Off the east coast, in the Sea of Japan, we find the island of Ulleung

The south



In the south, winter is less cold than in the center-north, however, the average temperature in January exceeds freezing only on the south coast (see Mokpo, Busan). Summer is hot and muggy here as well.

Busan

Here are the average temperatures of Busan, located on the southeastern coast, which in winter is the warmest area of the country.
Busan - Average temperatures
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)-1051014182223191482
Max (°C)8913182224272926221610
Min (°F)303241505764727366574636
Max (°F)464855647275818479726150

Near Busan, and along the southern coast, the sea is much less cold in winter, while in summer it gets a bit warmer than in Seoul, reaching 26 °C (79 °F) in August.
Busan - Sea temperature
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Temp (°C)141313141720232624211916
Temp (°F)575555576368737975706661

The southern island of Jeju (or Cheju) is even milder: here the average temperature in January is about 5/6 °C (41/43 °F). On the other hand, the winds coming from the continent pick up moisture from the sea before reaching the island, so here the winter is often windy and rainy.
Here are the average temperatures of Jeju City.
Jeju City - Average temperatures
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)34610141923242015105
Max (°C)8913182225293026211611
Min (°F)373943505766737568595041
Max (°F)464855647277848679706152

Typhoons

As mentioned, South Korea can be hit by typhoons. Typhoon is the name given to tropical cyclones in East Asia. Typhoons are accompanied with large amounts of rainfall and strong winds, and usually produce the greatest damage on the south coast and Jeju Island.
Typically, typhoons affect Korea from July to early October, with a higher probability in the first half of September. Sometimes they also arrive in the second half of June, when they are generally less strong and only affect the extreme south.

Best Time



Considering both the cold winter and the hot and rainy summer, the best times to visit South Korea are spring and autumn, especially the months of May and October. The latter can be preferred because it's less rainy (and it's outside the so-called yellow dust season). Moreover, in autumn you can admire the fall foliage in national parks.
As previously mentioned, the sea is warm enough for swimming from July to September, especially in the center-south.

What to pack



In winter: for Seoul and the center-north, bring warm clothes, such as a down jacket, gloves, a scarf, a hat. For the extreme south, Mokpo and Busan, warm clothes, such as a sweater, a jacket; scarf, gloves and a hat for the evening, possibly a raincoat or umbrella.
In summer: bring light clothes, of natural fibres, a light raincoat or umbrella, a scarf for the wind, a light sweatshirt for air-conditioned places.
It is customary to remove shoes before entering homes and temples, so it can be useful to bring shoes without laces, or that are at least easy to take off.