In the city of Limeira, located in the State of São Paulo, Brazil, the major ions of 30 rainwater samples, collected from Sep/2013 to Mar/2014, were quantified by ionic chromatography (ICS 90); and HCO3− was determined via Gran titration. Three source apportionment methods, namely Principal Component Analysis (PCA), air mass trajectory clustering and enrichment factor (EF), were used to identify the main sources of pollutants dissolved in rainwater samples. The concentration of ions (μeq L−1), of the samples was: Ca2+ > NH4+ > Na+ > HCO3− > Mg2+ > SO42− > NO3− > Cl− > K+ > H+, and pH = 5.6 in VWM. The first three components obtained via PCA explained 75% of the total variance correlation and indicated a strong contribution of pollutants from agricultural emissions in the studied region, possibly due to the proximity of rural areas. The generated trajectory clusters indicated a 70% contribution from continental sources in the studied area. EF showed that SO42−, NO3−, Cl−, K+, Mg2+ and HCO3− are from anthropogenic sources whereas Ca2+ is from crust and Na+ is from crust and anthropogenic sources. The anthropogenic sources, possibly associated with the region's agricultural activities, mining, industries and heavy vehicle traffic. In addition, it was verified the negative impact the fire outbreaks in the State of São Paulo had on the quality of the air in Limeira. Finally, the ionic concentrations in rainwater samples collected in the urban area of Limeira were compared with data from monitored cities in Brazil and throughout the world.