The objective of this study is the analysis of stable isotopes (δ18O and δ2H) of rainwater in southwest Spain to determine the local meteoric line and to investigate the origin of the vapor masses. A 5-L polyethylene bottle containing paraffin oil to impede evaporation was installed at two samplings stations: Plaza de España located in the city of Seville (Urban area) and Doñana National Park at the province of Huelva (Rural area). We evaluated 72 samples taken from 2014 to 2018. Isotopic samples were analyzed with a Laser spectroscopy system (Model L1102-i, PICARRO). Results show a representative Local Meteorological Water Line (LMWL) for southwest Spain and isotopic variations and theirs dependence on the origin of the vapor masses using satellite images of meteorological situations and local meteorological data. Furthermore, the importance of thermal influences and the existence of a continental effect will also be analyzed by comparing the isotopic signals of the two locations.