The outbreak of COVID-19 is having a significant impact on people’s concern on health and healthcare systems. Increased research outputs in all areas related to COVID-19, such as disease risk assessment, prediction, early warning, and treatment, have become available. Previous research suggests that there is a relationship between air quality and the disease. This paper investigated the impact of the climatic and environmental conditions on the basic reproduction number (R \(_0\) ) in areas of Australia, South Korea, and Italy using local temperature, humidity and air pollutant data, confirmed case data, and the Quasi-Poisson regression based distributed lag non-linear model (DLNM). The results show that the temperature and humidity conditions have a lag and persist influence on short-term R \(_0\) , and seasonal factors seem to have an apparent decorating effect on R \(_0\) . PM \(_{10}\) appears to be the primary pollutant that affects the excess morbidity. Moreover, O \(_3\) , PM \(_{2.5}\) , and SO \(_2\) as perturbation factors appear to have a cumulative effect. These results improves our understanding of the correlation between climatic and environmental factors and COVID-19 prevalence, which would benefit further studies in related areas.