Before revision:  We find a similar influence of the temperature and relative humidity on  effective reproductive number (R values)of COVID-19 for both China and the U.S. before lockdown in both countries: one-degree Celsius increase in temperature reduces R value by about 0.023 ( 0.026 (95\% CI [-0.0395,-0.0125]) in China and  0.020 (95\% CI [-0.0311, -
After revision:  We find a similar influence of the temperature and relative humidity on effective reproductive number (R values)of COVID-19 for both China and the U.S. Conclusions: Higher temperature and higher relative humidity potentially suppress the transmission of COVID-19. Specifically, an increase in temperature reduces R value by about 0.023 ( 0.026 (95\% CI [-0.0395,-0.0125]) in China and 0.020 (95\% CI [-0.0311, -