The Modèle Atmosphérique Régional (MAR) is a regional climate model especially developed for studying the near surface climate and surface mass balance of both polar ice sheets. This dataset includes MAR outputs from version 3.12.0 of the model (MARv3.12) forced by the ERA5 reanalysis for a domain surrounding Greenland. The data are provided at a spatial resolution of 15km and temporal resolution of 1 hour, for the June-July-August (JJA) summer months during 1980-2020. With respect to MARv3.11, the main improvements of MARv3.12 are the geographical projection used by MAR which is now the standard Polar Stereographic EPSG 3413, a correction of an important bug impacting the snow temperature at the base of the snowpack, a conservation of water mass in the soil impacting water fluxes over the tundra, and a continuous conversion from rainfall to snowfall from 0°C to -2°C as input of the snow model instead as a fixed one at -1°C. The following MAR variables are included in this dataset: lat/lon coordinates, ice sheet mask, surface height, meltwater, 10-meter u/v-wind components, and relative humidity.