Temperature and humidity affect the dengue occurrence in several subsequent months. We found that monthly maximum temperature and relative humidity were associated with dengue transmission through a 4-months lag period (highest effects in two months) which includes the time of replication and development of mosquito and the incubation period of the virus (time of replication both in vector and host). Therefore, observed lag effects were biologically plausible and consistent with the findings of other studies (Arcari et al., 2007; Hii
et al., 2012; Wu et al., 2007). A previous study in Dhaka reported the positive association between maximum temperature, relative humidity and dengue which is consistent with our findings (Karim et al., 2012). They also observed the highest lag effects at two months which is similar to our observation. An accurate early warning system to predict dengue epidemics and enhance the effectiveness of preventive measures largely relies on the sufficient lag time. Thus, four months lag time could be sufficient to warn people about the possible disease out- break and take necessary measures to prevent the epidemic.