Tropical forest ecosystems play a significant role in controlling the global carbon cycle. Several bio-meteorological parameters control the carbon dynamics of a forest ecosystem. We have studied the bio-meteorological processes of a tropical semi-deciduous forest in northeast India to understand the dynamics of the net ecosystem exchange (NEE). On a monthly scale, it is observed that mostly the leaf area index, incoming radiation, vapor pressure deficit, and air temperature control the carbon transfer processes. Furthermore, the diurnal patterns of rainfall and associated cloudiness during the monsoon season indirectly control the carbon uptake by modulating the incoming radiation. The pre-monsoon season is the most preferred, while the winter season is the least favorite time for carbon uptake by this forest. The respiration component of the studied forest ecosystem is higher than the other similar ecosystems in India. The estimated annual NEE of the forest was +177 and -31 gC m−2 yr−1 for 2016 and 2018, respectively. The forest's annual gross primary productivity (GPP) for 2016 and 2018 was estimated as 2693 and 2564 gC m−2 yr−1, respectively.