The global climate change has led to the distribution of Bactrocera dorsalis from its origin in Southeast Asia to mainland China, which is situated at latitudes similar to Jeju Island, South Korea. In order to evaluate the establishment of B. dorsalis in Korea, it is necessary to determine the climate suitability. When the parameters of CLIMEX model were adjusted to include Wuhan region in China as the northern limit, the model outputs explained well the distribution and occurrence characteristics (namely the annual number of generations) of B. dorsalis in major distribution regions in the world. In IPCC/RCP 8.5 scenario, the establishment of B. dorsalis was suitable to a small part of Jeju Island in the 2010s. The range might gradually spread until the 2090s, with many parts of the lowlands of Jeju Island being marginal to optimal in suitability. The present CLIMEX model with parameters that adjusted to known northern limit will be useful for annual risk mapping to facilitate a monitoring system for early detection of a possible founder population of B. dorsalis in Jeju, South Korea.