Chloride-induced corrosion on reinforcing steel is one of the main causes that may shorten the service life of concrete structures. Recent studies have found that the deterioration process of these structures is highly influenced by material properties, environmental factors (exposure conditions) and climatic conditions (such as temperature, humidity, seasonal variations, etc.). For infrastructure in coastal areas of Vietnam, it has been observed that corrosion occurs within 10 to 30 years of service. The purpose of this paper is to carry out the service life prediction of reinforced concrete (RC) structures in coastal areas in Vietnam. A model simulation of chloride penetration into concrete before and after repair and under various climatic conditions is developed in FreeFEM++ software to assess the effects on structure service life. A case study is conducted in three coastal cities in Vietnam where the annual temperature and humidity vary. The results show that chloride ingress into concrete is highly influenced by weather conditions. In addition, some maintenance strategies, that are appropriate with the practical conditions in each area in Vietnam, are recommended to prolong the service life of corroding RC structures.