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As the main solid waste disposal method in China, landfill sites are considerable sources of methane (CH 4) and carbon dioxide (CO 2). This study characterized the seasonal variation of CH 4 and CO 2 effluxes at a large and well-managed final covered landfill site in China. A three-year monitoring program was conducted. There were two different seasonal variation patterns for hotspot and non-hotspot' CH 4 and CO 2 effluxes. For non-hotspots, the CH 4 and CO 2 effluxes' seasonal variations were mainly affected by the seasonal change of the landfill's cover soil respiration activity, particularly the CH 4 oxidation capability. CH 4 had a higher efflux in winter; in other seasons, the CH 4 efflux fluctuated around 0; the CO 2 effluxes were (1) increased in spring and peaked in summer or early autumn; (2) then, they decreased to a minimum value in late autumn or early winter; and (3) fluctuated with the CH 4 efflux in winter. The CH 4 emissions in winter account for 60.4–84.4% of the all year outputs. For the hotspots', the CH 4 and CO 2 effluxes seasonal variations were mainly determined by the seasonal change of the landfill cover's soil gas permeability. The ratio of CH 4 emissions in winter to the all year outputs range from 17.4 to 68.7%. Unlabelled Image • Two different seasonal patterns for hotspots and non-hotspots CH 4 and CO 2 effluxes • CH 4 emissions of non-hotspots in winter account for 60 to 84% of all year outputs • CH 4 emissions of hotspots in winter account for 17 to 69% of all year outputs [ABSTRACT FROM AUTHOR]