This year Dydd Miwsig Cymru will be held on Friday 10 February, but spilling over into Saturday for some events, e.g. this one posted by @siaronjames in Wrecsam.
There is information about Dydd Miwsig Cymru on the Welsh government website, with suggestions of playlists on Spotify that may interest you.
But if you haven’t come across it yet, we have our own amazing thread on the forum where SSiWers have been posting music videos since 2014, so it’s a fantastic collection - have a look at Welsh Music Videos and Audio Files
If you come across any other events celebrating Welsh Music Day, feel free to post them here