The CHELSA dataset provides high-resolution (30 arc sec) temperature and precipitation climatologies derived from downscaled ERA-Interim reanalysis data. The temperature algorithm uses statistical downscaling, while the precipitation algorithm incorporates orographic predictors (wind fields, valley exposure, boundary layer height) and includes bias correction. The dataset includes monthly temperature and precipitation climatologies for 1979–2013. CHELSA shows improved accuracy in species distribution modeling compared to other products, with better precipitation predictions than temperature. The dataset is validated against multiple sources, including station data and other climatologies, showing high correlation with GHCN, FAO, and other datasets. CHELSA outperforms WorldClim and ERA-Interim in several regions, particularly in complex topography. The dataset is available as GeoTIFF files with bioclimatic variables for ecological applications. The algorithm uses a combination of statistical downscaling, interpolation, and bias correction to improve accuracy, particularly in mountainous and tropical regions. The dataset is freely available for research and has been validated across multiple regions and datasets, demonstrating its reliability for ecological and environmental studies.The CHELSA dataset provides high-resolution (30 arc sec) temperature and precipitation climatologies derived from downscaled ERA-Interim reanalysis data. The temperature algorithm uses statistical downscaling, while the precipitation algorithm incorporates orographic predictors (wind fields, valley exposure, boundary layer height) and includes bias correction. The dataset includes monthly temperature and precipitation climatologies for 1979–2013. CHELSA shows improved accuracy in species distribution modeling compared to other products, with better precipitation predictions than temperature. The dataset is validated against multiple sources, including station data and other climatologies, showing high correlation with GHCN, FAO, and other datasets. CHELSA outperforms WorldClim and ERA-Interim in several regions, particularly in complex topography. The dataset is available as GeoTIFF files with bioclimatic variables for ecological applications. The algorithm uses a combination of statistical downscaling, interpolation, and bias correction to improve accuracy, particularly in mountainous and tropical regions. The dataset is freely available for research and has been validated across multiple regions and datasets, demonstrating its reliability for ecological and environmental studies.