Sources and licenses

WeatherTell.com combines weather data from several open sources with our own calculations. This page lists the sources we use, what we use them for and under which license. In articles and tables we also name the source where it is used.

Weather forecasts

The current weather and the 14-day forecast come from Open-Meteo, which combines the output of established weather models. Open-Meteo data is licensed under CC BY 4.0. Place search also runs through Open-Meteo, based on GeoNames (CC BY 4.0).

For forecasts in articles we sometimes use the ensemble forecasts of the ECMWF and of NOAA’s GFS model, also via Open-Meteo.

Climate data

The monthly climate tables on city pages, and many figures in our articles, are calculated from the ERA5 reanalysis of the Copernicus Climate Change Service, retrieved via Open-Meteo. These are model averages for a grid cell, not weather station records, as we also note under each table.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.

For measured snow depth in Austrian ski resorts we use data from GeoSphere Austria (CC BY 4.0). Seasonal outlooks and El Niño information come from NOAA’s Climate Prediction Center (public domain).

Sea temperature, air quality and pollen

Sea temperatures come from Open-Meteo’s Marine API. The hay fever and air quality forecasts come from Open-Meteo’s Air Quality API, which is based on the Copernicus Atmosphere Monitoring Service (CAMS).

Contains modified Copernicus Atmosphere Monitoring Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.

Sunrise, sunset and daylight

We calculate sunrise and sunset times, daylight and polar night ourselves, using NOAA’s solar position algorithm and the open-source astronomy-engine library.

Photos

The photos in our articles come from Wikimedia Commons. They are free to use under the license shown with each photo, such as CC BY, CC BY-SA, CC0 or public domain. Under every photo we credit the author, link to the source and name the license.

Report a source or photo

Spotted a mistake in a credit, or have a question about a photo or the data? Email info@gianboender.nl.