I like the mood this has going, it's appropriately chill. A couple observations I had:
The count-off isn't in time with the song, this makes it hard to start playing and leads to a lot of false starts.
The, I'm just gonna call them "timing squares" should be a bit brighter, as they're hard to see and kinda blend into the background. I would think a lot of people would focus entirely on these squares because they let you know your exact timing, which means Darkness mode is easier than it should be.
Similarly, the effects for wind direction are easy to miss. Having the effect maybe last a bit longer or stand out more, i.e. with color effects, would make them easier to spot. (Take this with a grain of salt, I know I can get tunnel vision in these types of games) The sound cue you have for wind is much appreciated, though. It's just that I wish I could react in time.
I don't think wind should take effect on the first beat of the song. It's hard to predict and also leads to a bunch of false starts.
On the other hand, Wind becomes easier to deal with when you look at the entire board, but because the player can't really look in two places at once, then they're losing out on their timing information (again, gain of salt, tunnel vision)