I have the same problem with weewx. I have installed in the 12/2019 and all worked fine. Now I notice the error without any changes in my weewx configurations. My station ID is f06852fd
These numbers are in connection with Waves. They appear when Wave layer is selected and under towns near the sea. But they do not correspond to wave heights or wave period. They change when you change the wave model.
There is probably someone in the Windy team who can explains them or just say that’s a bug?
It is possibly due to a bad synchronisation of the time slider. Try to move the time slider with the arrow keys of your keyboard.
When you select the Wave or Swell layers and choose a location at sea, move a bit forward/backward the time slider using the arrow keys to synchronise layer particles movement, wave rose and diagram. I find that it deletes the display discrepancies.