Kim, Y.-K.; Kim, H.; Seo, J.-W.; An, H.-Y., and Choi, Y.-H., 2017. Meteorological analysis of the sea fog in winter season on Gyeonggi Bay, Yellow Sea: A case study for the 106-vehicle pileup on February 11, 2015. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 124–128. Coconut Creek (Florida), ISSN 0749-0208.The winter sea fog in the Yellow Sea is generally known as steam fog which is created when a cold and dry air mass (e.g., Siberian high) flows over warm sea surface. The status of the atmospheric boundary layer frequently changes by various interactions between atmosphere and ocean, because the west coast of the Korean peninsula has a complicated shoreline by numerous islands and rias coast. Therefore, the sea fog around this area is temporarily generated in unexpected place and it is reduced the visibility severely. The 132 casualties (3 dead, 129 injured) were occurred by the 106-vehicle pileup over the Yeongjong Bridge on February 11, 2015, because of the sea fog on Gyeonggi Bay in the Yellow sea. In this study, synoptic weather analysis and numerical weather modeling were performed to understand causes of sea fog. As a result, the atmospheric boundary layer of Gyeonggi Bay was generally stable because of a stagnant high pressure system when the accidents took place. In addition, low level air under the atmospheric boundary layer was colder than SST on Gyeonggi Bay. It means that the sea fog may be generated by the temperature difference between sea and air.