What WhenToGo is built on
Every report uses 10 years of measured weather for the place you asked about, drawn from several independent kinds of sources and cross-checked against each other.
Half-hourly instrument observations — temperature, wind and gusts, visibility, and observed events such as rain, fog, snow or thunderstorms.
Long-running archives built from satellite and ground measurements, covering precipitation, cloud cover, sun times and radiation for any coordinates on Earth.
Place registries, elevation models and earthquake catalogues — the parts of a Geo and Climate passport that do not change with dates.
Attribution
Airport observations via the Iowa Environmental Mesonet archive (Iowa State University), originating from national weather services. Climate archive: ERA5 reanalysis produced by the Copernicus Climate Change Service (C3S) / ECMWF, used under CC-BY 4.0 — neither the European Commission nor ECMWF is responsible for any use of this data. Earthquake catalogue: U.S. Geological Survey. Elevation models: Copernicus DEM and SRTM. Place registry: GeoNames, used under CC-BY 4.0. WhenToGo processes and presents this data; the statistics and wording are ours.