Where the data comes from, what the site stores, and what it can't promise
Weather forecast
Hourly wind speed, gusts, temperature, and sunrise/sunset times come from Open-Meteo, used under CC BY 4.0. supdawg computes a SUP-conditions score from this forecast; the underlying weather data itself isn't altered.
Location search
Place search and place names use Photon, built on OpenStreetMap data (© OpenStreetMap contributors, ODbL), with Open-Meteo's geocoder as a fallback. Map images are loaded by your browser directly from PDOK (Kadaster), which therefore sees your IP address, as it would for any website's images.
Your location
On your first visit the site uses the approximate location that comes with your internet connection to open on a nearby spot. It is used once to render that page and is not stored. The "use my location" button asks your browser for a precise position; that only happens when you press it.
What this site stores in your browser
Nothing, until you press the star. Starring a spot saves it in a small cookie in your browser (sd_spots) so the chip row can show it again; once you have a saved spot the site also remembers the last spot you viewed (sd_last) so it opens there next time. Both stay in your browser for up to 90 days, are never sent anywhere except back to this site to render your page, and disappear when you unstar every spot or clear cookies. There are no analytics, no tracking, no accounts and no third-party scripts.
Scoring logic
The site's code is open source (MIT licensed) - see the repository on GitHub.
About this site
supdawg is a free, non-commercial hobby project. The source code is on GitHub; if something looks wrong or you have a question, open an issue.
No guarantee
The verdicts on this site are computed from a public weather forecast using fixed thresholds. Forecasts are uncertain, conditions on open water can differ from the forecast at any moment, and this site cannot know your skill, your board or the water you are on. Use it as one input, not as a decision. You are responsible for your own safety; check official warnings from KNMI before going out.