There are two types of sea fog affecting the Shandong Peninsula’s southern shore, namely widespread sea fog and coastal sea fog. Although the coastal sea fog predominantly causes considerable interruptions to port operations and coastal activities, existing studies on this phenomenon remain limited and lack depth. This study aims to explore the spatio-temporal distribution patterns of the coastal sea fog events in the Shandong Peninsula’s southern shore from 2008 to 2023, as well as the underlying causes, using data of coastal stations, reanalysis grid data and satellite observations. The major findings are as follows. (1) Based on the geographical spread of fog areas, we further divide the coastal sea fog into 5 types under 5 kinds of synoptic situations, and the monthly variations of each type’s frequency are significantly different. (2) The spatio-temporal evolution of coastal sea fog displays significant diurnal variations. Rapidly changing synoptic systems have a substantial influence on the morphology of fog areas, while sea surface temperature and sea-air temperature difference play crucial roles in fog development under slowly changing synoptic situations. (3) Most coastal sea fog episodes are accompanied by sea-land breeze processes. There is an essential temporal correlation between the emergence of sea fog and the establishment of land breeze circulation, both of which demonstrate consistent intermonthly fluctuations. This study suggests that the sea-land breeze circulation may play an important role in the formation of coastal sea fog along the Shandong Peninsula’s southern shore. To better understand this mechanism, additional research should be conducted utilizing high-resolution numerical models.