About
Swellcloud is a comprehensive marine weather and surf forecasting API designed for developers building ocean-aware applications. The platform delivers high-resolution global wave forecast data via a straightforward REST endpoint, enabling integration of wave height, peak wave period, wave direction, secondary swell height and direction, wind wave height and direction, wind speed, and wind direction into any product or pipeline. Two forecast models are available: the Swellcloud Default (GFS-based) model offering 0.25° (~28 km) resolution with 4x daily updates and a 16-day forecast window, and the CMEMS Global Wave High-Resolution model offering 1/12° (~9 km) resolution with satellite data assimilation and a 10-day window. Responses are returned as JSON and support both SI (meters, m/s) and UK (feet, mph) unit systems. The API is accessed via a single GET endpoint with latitude, longitude, variable selection, model choice, units, and time range as query parameters. Authentication is handled through an API key header. An interactive web playground is available for exploring queries, visualizing forecasts, and testing requests before integrating into production systems. Swellcloud is ideal for surf forecast apps, sailing and maritime navigation tools, coastal condition dashboards, ocean research platforms, and any application requiring reliable, structured marine weather data. A playground test key is available immediately; production keys are issued after a brief review process.
Key Features
- High-Resolution Global Wave Forecasts: Access forecasts at 0.25° (~28 km) resolution via the GFS model or 1/12° (~9 km) via the CMEMS model with satellite data assimilation, covering up to 16 days ahead.
- Comprehensive Marine Weather Variables: Query significant wave height, peak wave period, wave direction, secondary swell height and direction, wind wave height and direction, wind speed, and wind direction in a single API call.
- Simple REST API with JSON Responses: A single GET endpoint with intuitive parameters (lat, lon, vars, model, units, start, end) returns structured JSON data ready for immediate use in any application.
- Interactive Web Playground: A browser-based interface lets developers visually position markers on a map, select variables, run queries, and preview forecast charts before writing a single line of code.
- Dual Unit System Support: Switch between SI (meters, m/s) and UK (feet, mph) units with a single query parameter to match the requirements of any target audience or application locale.
Use Cases
- Building surf forecast web and mobile applications that display real-time wave height, period, and swell direction for specific coastal locations.
- Powering sailing and maritime navigation tools with reliable wind speed, wind direction, and wave condition data for route planning.
- Integrating marine weather data into coastal tourism platforms to display beach and surf conditions for travelers and holidaymakers.
- Supporting ocean and climate research workflows by programmatically fetching historical and forecast wave data for analysis and modeling.
- Creating automated surf condition alert systems that notify users when wave height or period crosses a defined threshold at their favorite breaks.
Pros
- Instant Access with Free Playground Key: A test API key is provided immediately, allowing developers to explore endpoints, test queries, and evaluate data quality without waiting for account approval.
- Multiple High-Resolution Forecast Models: The choice between GFS and CMEMS models gives developers flexibility to optimize for forecast range, spatial resolution, or update frequency depending on their use case.
- Broad Variable Coverage: Unlike many surf APIs that return only basic wave height, Swellcloud includes secondary swell, wind waves, and full wind data, enabling richer surf condition analysis.
- Clean, Developer-Friendly Design: Standard REST conventions, clear documentation, cURL examples, and a web playground make integration straightforward for developers of all experience levels.
Cons
- Production Key Requires Manual Review: Unlike fully self-serve APIs, production access requires submitting a request form and waiting for email approval, which can slow down development timelines.
- Long-Range Queries Can Be Slow: Queries spanning the full 16-day forecast range can take up to 2 minutes to process, requiring client-side caching strategies for production performance.
- Niche Domain Focus: The API is purpose-built for marine and surf data; it is not suitable as a general-purpose weather API for atmospheric or terrestrial weather conditions.
Frequently Asked Questions
How do I get an API key for Swellcloud?
A free playground test key (test_playground_key_12345) is available immediately for exploring the API. For production use, you can request an API key via the form on the Swellcloud website or by emailing [email protected]. Production keys are reviewed and issued by email.
What forecast models does Swellcloud support?
Swellcloud supports two models: the default GFS-based model at 0.25° resolution with 4x daily updates and a 16-day forecast window, and the CMEMS Global Wave High-Resolution model at 1/12° resolution with daily updates, satellite data assimilation, and a 10-day forecast window.
What marine weather variables are available?
Available variables include significant wave height (hs), peak wave period (tp), peak wave direction (dp), secondary swell height (ss_hs), secondary swell direction (ss_dp), wind wave height (ww_hs), wind wave direction (ww_dp), wind speed (wndspd), and wind direction (wnddir).
How do I authenticate requests to the API?
All API requests require an API key passed via the X-API-Key HTTP request header. For example: curl -H "X-API-Key: YOUR_API_KEY" "https://api.swellcloud.net/v1/point?lat=50.087&lon=-5.318".
Can I request data in feet and mph instead of meters and m/s?
Yes. Add the query parameter units=uk to any request to receive wave heights in feet and wind speeds in mph. The default is units=si (meters and m/s).
