Changes in farming systems are dominated by changes in global climate and local environment, apart from the non-climatic drivers. Given the challenges in partitioning the contribution of climatic and non-climatic factors to the changes in farming systems, this paper aims to assess the types and changes of coastal farming systems, the farmer perceptions of the causes of the changes in farming systems, and the relationship between the infuencing factors and perceptions. A structured interview schedule was used to collect data from 381 randomly selected coastal households during September–October 2018. The random forest classifcation model was applied to estimate the relative importance of the farmers' characteristics on their perception of causes of changes in farming systems. This study reveals that the coastal farmers had mostly semi-subsistence type of mixed farming systems, which were going through dynamic changes in terms of their sizes and number of farmers. In general, the participation in rice, vegetables, and livestock farming was decreasing but increasing in fsheries, forestry, and fruit farming. Most (95.5%) of the farmers had to change at least one of the farming enterprises over the past decade (2009–2018) compared with the previous decade (1999–2008). About two-thirds of the farmers perceived that climate change had caused changes in their farming systems. Compared with the eastern coasts, the farmers in the western coasts tended to blame climate change to a higher extent for the effect on their agricultural activities. The random forest model outputs imply that the farmers who are younger in age and with less formal education, larger family, and smaller farmland should be supported with scientific knowledge on causes of changes in farming systems. This could help them more aware of climate change issues related to agriculture and increase their enthusiasm to take part in adaptive changes in farming systems.