We document the occurrence in December 2015 of unprecedented high monthly mean temperatures in the observational record of mountain sites in the eastern Alps. For the first time in the last 150 years mean December temperature exceeded 0 °C at elevations between 2100 and 2500 m, with December mean anomalies exceeding 6.5 °C with respect to the 1971–2000 mean.

We found consistent improvements in the high resolution (~12 km) vs. the medium resolution (~50 km) RCM and coarse scale GCM simulations. Even when RCM results were upscaled at the resolution of the GCMs some added value was found. We also found that the RCM downscaling substantially modulates the GCM-produced precipitation change signal in future climate projections (2070-2099 compared to 1976-2005).