Methodology

Matching days come from ERA5 hourly fields (2021–2025 for the full product; this Iberia build uses the Jan–Mar 2021 development window), aggregated to local solar days at 0.25° (~28 km). Local day for each cell runs midnight to midnight at UTC offset round(lon / 15) hours.

This is a recent-weather sample, not a 30-year climate normal. Microclimates (San Francisco fog, coastal breezes) average out at this grid scale.

Map criterion: daily max wet-bulb temperature (Stull 2011 from 2 m temperature and dewpoint), plus optional caps on cloud cover, precipitation and wind gust.

Contains modified Copernicus Climate Change Service information (2026). Neither the European Commission nor ECMWF is responsible for any use of this information. ERA5 via NSF NCAR Curated ERA5 on AWS Open Data (DOI 10.5065/BH6N-5N20). Cities: GeoNames, CC BY 4.0. Basemap: OpenFreeMap / OpenMapTiles / OpenStreetMap contributors.