Objective: To analyze the correlation between weather, population size and cases of COVID-19 in the capitals of Brazil .
Methods: All confirmed cases of COVID-19 infection, from the first confirmed case from February 26 until May 01, 2020 were included . For weather variables, average temperature (°C), dew point (°C), average humidity (%) and wind speed (m s-1) were extracted from the Instituto de Meteorologia database . The population size of each capital was used as a control variable, with data obtained from Instituto Brasileiro de Geografia e Estatística . Spearman rank correlation tests were utilized to examine the correlation between variables .
Results: The analysis showed a significant and strong positive correlation between the total cases of COVID-19 and the population size (p <0,01). There was a significant positive correlation with the average humidity of the air and cumulative cases (p <0,05). There was no significant correlation with other climate variables . Conclusion: Our results confront some expectations commented around the world about a possible seasonality of COVID-19 during periods of low humidity and can assist government and health authorities in decision making to control the pandemic . Studies in other regions are important to strengthen the findings.