An accurate tide forecast in our area is essential for competitive sailing and the Windy app does not provide this information. We can access today predictions from various other sources but it would be really good to have this info on your app. Our most accurate source of tidal data is http://www.ukho.gov.uk/EasyTide/EasyTide/ShowPrediction.aspx?PortID=0068C&PredictionLength=7
I expect each country has a similar source of data and I guess it would be a lot of work to get permission from every country - but well worth it for sailors, windsurfers etc...
I am fairly certain that there is a tide forecast available.
You can find it in the incon bar below the weather model options.
Locate that and click "more layers" and you should be able to find an option called "tide forecast".