See Image...

Test performed on Everon map on ridge between Bell Pit Lake and Cheval-Gin Lodge (Grid100 026 at 310m).

This is a Southerly wind. It is coming out of the South, blowing to the North, which is correct. Note the tree bend is correct. Hard to tell since this is a still image, but grass is also moving correctly. On the other hand, the flag is waving like there is a Northerly wind. I have tested all directions, and it appears the flag is opposite of what it should be.

In addition, the prompt and interface for wind always displays that the wind direction is North. For that reason, you can never actually set the wind direction to North, since the interface always shows North as the current setting. See image... This is the prompt after I set the wind to West.

I also tested a random location on Arland with the same results.