Temperature distribution in coastal aquifers is the consequence of different thermal sources, including groundwater recharge, seawater infiltration, atmospheric temperature, and geothermal heating. While previous studies have investigated the seasonal changes in temperature in the first upper meters of the aquifer (Li et al, 2006; Vandenbohede and Lebbe, 2011), and the impact of geothermal warming on the increase in groundwater temperature with depth (Parsons, 1970), there is still a lack of comprehensive information on the distribution of temperature in coastal aquifers considering all the possible thermal sources. To fill this research gap, this study focused on the Motril-Salobreña aquifer (Spain) and proposed a generic theoretical model of temperature distribution. The model took into account temperature sources from both the surface (recharge, air temperature, and seawater infiltration) and the bottom of the aquifer (geothermal heating). The model was adapted to reproduce the real conditions with the calibration of hydraulic properties and other relevant parameters. The temperature data of three wells located at distances of 285 m, 300 m, and 700 m from the coastline were used to validate the model. The model results revealed that the distribution of temperature was closely related to the position of the freshwater-saltwater interface (FSI). The flow patterns established in coastal aquifers due to variable density forced groundwater heated in the base of the aquifer to ascend, generating a thermal plume along the FSI. This created a thermal barrier, which differentiated the temperature of the saltwater domain from the freshwater domain. The models also showed that the position of the toe of the FSI was dependent on the geothermal gradient because of its influence on water density. Aquifers with higher heating would exhibit a different thermal profile, which could affect the position of the FSI and have implications for the temperature distribution of the aquifer.