About OpenSwells

Free, open-source surf reports and swell forecasts · GitHub

Overview

A free, open-source surf report and 16-day swell forecast for 170+ locations. Reports and forecasts come from The Environmental Modeling Center Operational Wave Models. New forecasts are received every 6 hours.

Previously

This project was previously a 3-day forecast for my local beach using an LSTM network, and later graph neural networks (site, github). I have since expanded it to a 16-day forecast for 170+ locations thanks to the Environmental Modeling Center and NOAA.

Running the app

For local development, two repos work together: grib-parse-collect downloads the wave model GRIB files and renders the forecast layers, and open-swells-app serves the map. Clone them side by side — the --local flag copies generated layers into the sibling open-swells-app/data/forecast/ directory.

$ git clone https://github.com/open-swells/open-swells-app
$ git clone https://github.com/open-swells/grib-parse-collect
$ cd grib-parse-collect && ./run.sh --local --verbose
$ cd ../open-swells-app && go run ./server
Go to localhost:8081

Dependencies

open-swells-app — Go 1.21+. Runs without configuration (PORT, DB_PATH, and FORECAST_DIR are configurable).
grib-parse-collect — Python 3.13+ managed with uv (pygrib, numpy, scipy, matplotlib, shapely, geojson), plus rsync for the --local copy step.
--verbose shows a progress bar while the parser runs; the full log is written to grib-parse-collect/logs/grib-run.log. A full 16-day run processes 129 forecast hours — use --limit <n> for a quick check.

Resources and tools