In summer, the influence of the North Pacific high-pressure system brings hot, humid weather with temperatures soaring as high as 35 °C (95 °F) on occasion.
In winter, the city is topographically influenced by expanding Siberian High-pressure zones and prevailing west winds bring colder air to Korea.
The bitterly cold days are commonly known to come in three-day cycles regulated by rising and falling pressure systems.
[citation needed] The most pleasant seasons for most people in the city are spring and autumn, when azure skies and comfortable temperatures are typical.
The west of Seoul is an extension of the coastal plain starting from Incheon, and the altitude gradually increases as it comes to the east.
The influence of the Siberian high leads to significantly colder winter temperatures than would be expected at this latitude.
About every 4 to 6 days, a low-pressure trough will move through South Korea, bringing with it cloudiness and light precipitation.
The amount of precipitation locally depends mostly on the elevation of the station and the length of time that the air has been over the Yellow Sea.
The majority of the annual precipitation falls between late June and the middle of September, with rains fully developing along the entire peninsula by mid-June.
Although winds might not pose a problem, the associated rainfall can cause significant flash flooding, a very real threat during the rainy season, especially in rough terrain.
The mean temperature for Seoul in August is 26.1 °C (79 °F)[9] October is the transition month between the summer rainy season and the cold, dry winter.