Germany-wide annual Cloud Optimized GeoTIFFs (COG) of the cumulative precipitation weather index (WI) during the DWD 15→18 shooting phase of winter wheat, computed on the E-OBS 0.1° native grid (EPSG:4326). Each annual COG contains four bands: WI — cumulative precipitation during the shooting phase (mm) u_pheno — 1σ uncertainty from phenological window placement, derived from the PHASE BAM posterior standard error (mm) u_precip — 1σ uncertainty from precipitation interpolation, derived from the E-OBS v32.0e ensemble spread (mm) u_total — combined 1σ uncertainty: sqrt(u_pheno² + u_precip²) (mm) The file ro-crate-metadata.json is a RO-Crate 1.2 compliant JSON-LD document encoding full data provenance via Schema.org CreateAction, per-band variableMeasured entries with derivedFrom links, and ISO 19157-1 quality element classifications. Input data: PHASE COGs v1.0.0 (doi:10.5281/zenodo.19571847) and E-OBS v32.0e (KNMI/ECA&D). Processing software: WeatherIndicatoR v0.2.0 (doi:10.5281/zenodo.19631197).