Energy system outcomes are strongly influenced by weather conditions, which affect electricity demand, hydrogen demand, and other temperature-dependent energy uses, as well as electricity supply through wind, solar and hydro generation. For TYNDP 2026, the weather representation is enhanced by explicitly integrating future climate projections, ensuring that the analysis reflects expected climate change impacts over long-term horizons.
Climate and energy related variables considering the impact of climate on wind, solar and hydro energy generation are sourced from the Pan-European Climate Database (PECDv4.2), combining historical consistency with climate projections from the CMIP6 framework under the SSP2-4.5 emission scenario. For each TYNDP target year (2030, 2035, 2040 and 2050), weather conditions are represented by a pool of 30 candidate climate years derived from three climate models and a 10-year moving window around each horizon.
Simulating the full set of 30 climate years would lead to disproportionate computational effort with limited additional insight. Therefore, a statistical selection methodology is applied to identify three representative weather years per target year, preserving the diversity of renewable generation conditions and temperature-driven demand while keeping the modelling tractable.
The selection is based on key climate and energy related variables relevant for the European power system: wind, solar and hydro generation, as well as temperature indicators (heating and cooling degree days), derived by linking PECDv4.2 data with PEMMDB data.
These variables are aggregated at macro-regional level, normalised, and analysed using dimensionality reduction and clustering techniques (k-means) to identify distinct weather regimes. For each regime (cluster), a representative climate year is selected by identifying the climate year closest to the centroid of each cluster.
The three selected weather years are assigned probability weights reflecting the share of candidate years belonging to each weather regime in relation to all the 30 climate years. These weighted weather scenarios are used to combine simulation results from different climatic conditions into a single set of representative outcomes for each target year, constituting the climatic basis for demand profiling, renewable and hydro timeseries generation, and power market simulations, while also ensuring consistency for other climate-sensitive energy demands modelled in TYNDP 2026.
The full methodological description of the weather year selection, including data processing, statistical indicators, clustering techniques and probability weighting, is provided in Annex III.
