The Antarctic Peninsula (AP) is highly influenced by mesoscale cyclones originating from the Bellingshausen Sea that traverse the Drake Passage. These systems drive extreme weather, including strong winds and blizzards, significantly impacting regional meteorology and glacier behavior. However, their effects on the South Shetland Islands (SSI) glaciers in the northern AP remain insufficiently explored. This study analyzes two mesoscale cyclone events from summer and winter 2013 using in-situ observations, ERA5 reanalysis, and high-resolution simulations from the Polar Weather Research and Forecasting (PWRF) and the COupled Snowpack and Ice surface energy and mass balance model in PYthon (COSIPY) to assess their atmospheric and glaciological impacts. PWRF generated high-resolution meteorological fields (up to 1-km horizontal resolution), while COSIPY estimated energy and mass balance fluxes of the SSI glaciers for January and July 2013. PWRF showed improved accuracy over the ERA5 in the simulation of air temperature, surface pressure, wind speed, solar radiation, and orographic precipitation. Two case studies of mesoscale cyclones (7 January and 16 July 2013) revealed significant temperature drops, intense precipitation, and strong winds, leading to short-term glacier mass balance increases of up to 8 mm water equivalent per day (w.e.·day⁻¹) in summer and 26 mm w.e.·day⁻¹ in winter, respectively. The cooling was linked to cold air advection from the Weddell Sea, while enhanced precipitation and winds resulted from interactions between the low-pressure systems and the complex topography of the SSI and the northernmost AP. These findings underscore the key role of mesoscale cyclones in shaping local climate and glacier mass balance, highlighting the need for further high-resolution atmospheric and glaciological modeling in the region.