Specifically, when the average daily temperature increased by 1 degree Celsius, the risk of hospitalization for pneumonia on the same day decreased by 1% (95% CI: 0.3 1.7%); whereas when the humidity increased, the risk of hospitalization increased by 14.4% (95% CI: 0.2 - 30.7%) on the day of hospitalization; risk increased by 16.5% (95% CI: 9.5 - 23.9%) one day before hospitalization; and risk increased by 15.2% (95% CI: 8.2 - 22.7%) two days before hospitalization.