Data Sources & Methodology

Primary Weather & Climate Provider: Open-Meteo

Our core weather, air quality, marine and historical climate data are provided by Open-Meteo, an open-source weather API that aggregates model data and observations from multiple national and international meteorological services.

Licence

Open-Meteo’s API data are offered under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. This licence allows us to share and adapt the data, including for commercial use, as long as we provide appropriate credit, include a reference to the licence, and indicate where we modify or build upon the data.

In line with the Open-Meteo licence requirements, we include a clear attribution such as “Weather data by Open-Meteo.com” with a link to open-meteo.com wherever we display location-based weather information.

Open-Meteo APIs Used

Wandering Weather uses the following Open-Meteo APIs and datasets in various parts of the site:

• Weather Forecast API – Hourly and daily forecasts for temperature, apparent (“feels like”) temperature, precipitation, chance of rain, cloud cover, wind, humidity, and UV index for the next several days. These power our “Today” and multi-day forecast views and help calculate short-term comfort and rain risk.
• Historical Weather API – Reanalysis-based historical data (back to ~1940 in many locations) used to derive long-term climate normals, seasonal averages and typical extremes for each city and month.
• Air Quality API – Hourly forecasts of particulate matter and gaseous pollutants (such as PM_2.5, PM₁₀, ozone, nitrogen dioxide and sulphur dioxide), as well as air-quality indices. These support our air-quality summaries and flags.
• Marine Weather API – Sea surface temperature and wave forecasts (wave height, period, direction) for coastal locations, used on our coastal and beach-focused pages.
• Climate / Climate Change API (present or planned) – Model-based climate projections for future decades, where we show how a destination’s climate is expected to change under specific scenarios.
• Geocoding & Elevation APIs – Where used, we obtain or cross-check city coordinates, elevation and time zones using Open-Meteo’s geocoding and elevation services, which themselves rely on openly licensed geographic datasets.

Open-Meteo also provides up-to-date information on model update times and coverage, which we use to schedule our refresh processes appropriately.

Upstream Meteorological & Climate Data Providers

Open-Meteo in turn builds its forecasts and historical datasets from a range of national and international weather services, climate centres and satellite programmes. The following organisations and datasets are used within the Open-Meteo ecosystem and therefore indirectly support the data you see on Wandering Weather:

• Deutscher Wetterdienst (DWD) – German Weather Service atmospheric, ensemble and wave forecasts, including ICON and ICON-Wave models.
• European Centre for Medium-Range Weather Forecasts (ECMWF) – Global medium-range forecasts and reanalysis products such as ERA5 and ERA5-Land, used for both current weather and historical climate statistics.
• NOAA / NCEP (United States) – Global Forecast System (GFS) and related models, and high-resolution HRRR forecasts where applicable.
• Canadian Meteorological Centre (CMC) – Atmospheric and ensemble forecast data.
• Météo-France – Atmospheric and wave forecast data.
• Japan Meteorological Agency (JMA) – Atmospheric forecast data for Japan and surrounding regions.
• Norwegian Meteorological Institute (MET Norway), Chinese Meteorological Administration (CMA), Australian Bureau of Meteorology (BOM), Royal Netherlands Meteorological Institute (KNMI), Danish Meteorological Institute (DMI), UK Met Office, ItaliaMeteo / ARPAE and MeteoSwiss – Regional and national forecast models contributing to higher-resolution local guidance.
• Copernicus Marine Service – Global and regional ocean and wave products used within marine and wave forecasts.
• Copernicus Climate Change Service (C3S) – Climate reanalysis and projections (including ERA5 / ERA5-Land and CMIP6) underpinning historical climate datasets and future climate scenarios.
• Global Flood Awareness System (GloFAS) – River discharge and flood-risk simulations used within some hydrological and flood-related products.
• GeoNames – An open geographic database used by Open-Meteo’s location services for place names and coordinates.

Each of the services above publishes its own terms and licences, many of which are based on Creative Commons attribution-style licences or equivalent open government licences. Open-Meteo’s licence page provides links to the relevant licences for each provider, and our use of the combined datasets follows the conditions of those licences via Open-Meteo’s CC BY 4.0 terms.

Special Attribution Requirements

Marine Weather (Waves & Sea State)

Sea-state information on Wandering Weather (such as wave height, period and direction) is generated using ICON Wave forecasts from the German Weather Service (DWD), made available via the Open-Meteo Marine Weather API. In accordance with the Open-Meteo marine API documentation, we provide a clear attribution to DWD alongside our attribution to Open-Meteo whenever we display these marine data.

A typical attribution may read:
“Wave and marine forecasts generated using ICON Wave data from Deutscher Wetterdienst (DWD), via Open-Meteo.”

Climate Change & CMIP6 Projections

Where we display long-term climate change projections (for example, future changes in temperature or rainfall under specific emission scenarios), these are based on CMIP6 climate model output distributed via the Open-Meteo Climate/Climate Change API. Open-Meteo requires users of this data to clearly attribute both the CMIP6 programme and Open-Meteo, and we follow that requirement in our climate-related sections.

A typical attribution may read:
“Climate projections based on CMIP6 model output, processed and delivered by Open-Meteo.”

How We Transform & Use the Data

Open-Meteo provides gridded weather and climate data at hourly or daily resolution. Wandering Weather then performs additional processing to make this information more useful for travellers. This processing includes (but is not limited to):

• Converting units (for example, between metric and imperial), rounding values, and resampling data to daily, weekly or monthly summaries.
• Calculating long-term monthly “normals” and typical ranges (for example, 30-year averages, medians, and percentile values) for each city and month, using historical data from the Open-Meteo Historical Weather API and reanalysis datasets.
• Deriving secondary indicators such as:
  • “Feels like” comfort bands based on apparent temperature and humidity.
  • Rain-risk and “umbrella” style indices based on precipitation totals and probabilities.
  • Wind, UV and heat stress flags for particularly extreme days or hours.
  • “Best time to visit” and activity scores (for beach, city walks, hiking, etc.) that combine multiple variables (temperature, rainfall, UV, daylight, wind, air quality and sea temperature) into a single month-by-month ranking.
• Building location-specific narratives (for example, “Weather in July” summaries and packing advice) that describe what the numbers mean in plain language.

These transformations and interpretations are created by Wandering Weather and are not official products of Open-Meteo, ECMWF, Copernicus or any national meteorological service. Any errors in calculation, scoring or presentation are ours.

Location & Time Zone Data

We maintain our own database of locations (cities, regions and countries), including latitude, longitude, coastline flags and time zones. In some cases we use or validate this information against publicly available geographic datasets and geocoding services, including Open-Meteo’s own geocoding and the GeoNames database.

Time-zone handling is important when displaying sunrise and sunset times, daily breakdowns and hourly forecasts. We align all times to the local time zone of each location, using the time-zone metadata provided by Open-Meteo and/or standard IANA time-zone data.

Limitations & Disclaimer

All of the data we present, including forecasts, historical statistics and climate projections, are model-based or derived from model-based reanalysis. While these datasets are carefully produced and widely used in scientific and operational contexts, they can never capture every local micro-climate or short-lived weather event perfectly.

You should therefore treat Wandering Weather as a helpful planning tool, not as a guarantee of actual conditions. For safety-critical decisions (such as responding to severe storms, floods, heatwaves or bushfires), always consult your local national meteorological service, civil defence or emergency management agency and follow their official warnings and advice.

Wandering Weather is not affiliated with Open-Meteo, ECMWF, Copernicus, DWD, NOAA or any national weather service. All product and organisation names are the trademarks of their respective owners.

Attribution Summary

• Weather, air-quality, marine and historical climate data: Open-Meteo – open-meteo.com – licenced under CC BY 4.0 .
• Underlying forecast and reanalysis data: various national meteorological services and the Copernicus programme, including ECMWF, DWD, NOAA/NCEP and others, as detailed on the Open-Meteo licence page .
• Marine and wave data: ICON Wave forecasts from Deutscher Wetterdienst (DWD), via Open-Meteo.
• Climate projections: CMIP6 multi-model ensemble output, accessed via Open-Meteo’s Climate/Climate Change API.
• Geographic data: GeoNames and other open geographic datasets, where used, under their respective open licences.

If you have questions about how we use any particular dataset, or if you are a data provider and believe additional attribution is required, please contact us and we will be happy to clarify or update this page.