In a first step the performance of WRF will be tested and the model will be adjusted to the complex region of the Andes Mountains of Ecuador. Uncertainties in the model are assessed in an extensive sensitivity study encompassing various parametrization scheme combinations, e.g. cumulus convection, microphysics, land-surface models, radiation and PBL pyhsics. The model results are validated against observational data (in-situ measurements and remote sensing satellite data) to assure the accuracy of the hrCIS. The hrCIS is a set of area wide gridded variables like air temperature, precipitation, wind field, radiation, surface fluxes etc. and covers the time period December 1994 til November 2015 owing a spatial resolution of 4 km. In complex regions as the Andes Mountains such hindcast simulations facilitate analysis of recent climate trends in atmospheric conditions as well as its feedbacks to the ecosystems. Analysis of the temporal evolution of air temperature and precipitation for each ecosystem (Paramo, Rain forest, Dry forest) demonstrate that WRF successfully reflects the different characteristics. Further, the results highlights the ability to reproduce typical interannual variability of the climate indicators. With respect to climate trends in the study area an increase in air temperature can be recognized while precipitation reveals no trend.