Data Sources & Attribution
CityWeather365 relies on high-quality, openly licensed data from respected organizations. We are grateful to these providers and committed to proper attribution.
Weather Data
Open-Meteo
All historical weather data on CityWeather365 is provided by Open-Meteo, an open-source weather API. Open-Meteo aggregates and provides access to high-quality meteorological data from various sources.
Attribution (Required by CC BY 4.0):
"Weather data by Open-Meteo.com"
Data Used: Historical Weather API - daily and monthly averages for temperature, precipitation, sunshine hours, humidity, wind speed, and cloud cover
Time Range: 1994–2024 (30-year historical averages)
License: Creative Commons Attribution 4.0 International (CC BY 4.0)
Climate Reanalysis Data
Copernicus Climate Change Service (C3S)
The weather data provided by Open-Meteo is derived from the ERA5 reanalysis dataset, produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) for the Copernicus Climate Change Service.
Attribution (Required by Copernicus License):
"Contains modified Copernicus Climate Change Service information [2024]"
Dataset: ERA5 hourly data on single levels from 1940 to present
Description: ERA5 is the fifth generation ECMWF reanalysis for the global climate and weather. It provides hourly estimates of atmospheric, land, and oceanic climate variables with global coverage at 31km resolution.
License: Copernicus License (free for any use with attribution)
City & Geographic Data
GeoNames
City names, coordinates, country information, population data, and timezone information are sourced from the GeoNames geographical database, which contains over 25 million geographical names.
Attribution (Required by CC BY 4.0):
"City data by GeoNames.org"
Data Used: City names, coordinates (latitude/longitude), country codes, population figures, timezone identifiers
License: Creative Commons Attribution 4.0 International (CC BY 4.0)
Photography
Unsplash
City photographs used on CityWeather365 are sourced from Unsplash, a platform for freely-usable images contributed by photographers around the world.
Attribution:
"City photographs by Unsplash"
Content: City skylines, landmarks, and travel photography for featured destinations
License: Unsplash License (free for commercial and non-commercial use, no attribution required but appreciated)
Full Attribution Statement
Weather data by Open-Meteo.com
Contains modified Copernicus Climate Change Service information [2024]
City data by GeoNames.org
City photographs by Unsplash
Data Processing Methodology
CityWeather365 processes raw historical data to create the climate statistics displayed on our site:
- Data Collection: We query the Open-Meteo Historical Weather API for daily data from 1994–2024 for each city location using coordinates from GeoNames.
- Monthly Aggregation:Daily values are aggregated into monthly averages. For example, the "average high temperature in January" is the mean of all daily maximum temperatures across all Januaries in the 30-year period.
- Travel Score Calculation:We calculate a proprietary "travel score" (0-100) based on temperature comfort, rainfall, sunshine, humidity, and wind speed, weighted by typical traveler preferences.
- Quality Control: Data is validated for completeness and outliers are reviewed. Cities with insufficient data coverage are excluded.
Questions About Our Data
If you have questions about our data sources, methodology, or attribution, please contact us:
Email: data@cityweather365.com
Website: https://cityweather365.com/contact