In this study the Weather Research and Forecasting (WRF) model is used to dynamically downscale NASA Goddard Institute for Space Studies (GISS) GCM ModelE simulations over the Mediterranean in order to assess the grid size selection effect on the estimated climate change in this region. Results are presented for Athens (Greece) and Rome (Italy), the biggest cities at the
south-southeast Europe, which are located close to the sea. A multinesting approach is used with grid resolutions of 108 km, 36 km, 12 km, 4 km and 1.3 km. The NASA GISS GCM ModelE is used to simulate current and future climate using the RCP4.5 emissions scenario while WRF simulations are performed for October of 2010 and 2050. The sensitivity analysis assesses the estimated changes in temperature, precipitation and wind speed for the related cell in each grid that corresponds to the cities of Athens and Rome. The results show that increasing grid resolution significantly improves the spatial distribution of the examined parameters but does not add much value on the average projected change of the variable.