This study aims to evaluate the influence of meteorological factors on hospital admissions for pneumonia in children and elderly in Bauru and Pelotas cities, between 2009 to 2016. The health information was obtained from the Brazilian System Database and the daily average temperature and relative humidity from the meteorological stations of the National Institute of Meteorology and of the UNESP Meteorological Center. Descriptive analyses were performed to verify temporal trends and seasonal variations of meteorological variables and hospitalizations. Spearman correlation and Generalized Additive Model (GAM) Statistical methods were applied too. The results showed that Pelotas, presents the highest frequency of hospitalizations. It’s observed an increase in admissions in winter in both cities, except for children, in Bauru/SP, which occurs more frequently in the fall. The correlation was significant for low air temperature and high relative humidity. In addition, the GAM indicated a higher risk of hospitalizations with temperatures below 16°C and relative humidity above 40% (Bauru) and 80% in Pelotas. The increase in hospitalizations occurs in winter, and caused by the low temperatures and high relative humidity.