This dataset presents monthly gridded methane emissions from subtropical freshwater wetlands across the Southeastern United States spanning from 1982 to 2010, measured in nmol m-2 s-1. Each grid cell's methane flux prediction was adjusted based on the fractional wetland extent within that cell, utilizing data from the National Wetland Inventory (NWI) and the Wetland Area and Dynamics for Methane Modeling (WAD2M) product. The dataset includes mean monthly fluxes with no adjustment for wetland area (i.e., fluxes assuming hypothetical 100% wetland cover), as well as mean monthly fluxes adjusted for wetland area based on NWI or WAD2M, along with their respective standard deviations of the daily emissions for each month. Data are provided in NetCDF4 format. Lat: 25-40°N Lon: 95-75°W Period: 198201-201012 (for "CH4_Monthly_SEUS_unweighted.nc" and "CH4_Monthly_SEUS_NWI.nc") and 200001-201012 (for "CH4_Monthly_SEUS_WAD2M.nc") Temporal resolution: Monthly Spatial resolution: 0.0083° × 0.0083° (~1 km × 1 km) Unit: nmol m-2 s-1 Fill value: -9999