NZ Weather Forum

I have a lacross weather station and when the wind direction is from northerly quarter the graph
display is all over the place but other directions show much less variation. I know that nw winds are rather gusty and change direction a lot but it should average out. I am wondering if this could be caused by wrap around error (eg one reading of 350 deg then 010 degrees average as southerly) but have found nothing in manual or elsewhere on this and wonder if other weather stations have similar issues

Are we talking the graph for speed or direction? I expect you are referring to the direction indication, the Vane likely has a magnet in it that activates a number of reed switches to indicate direction. You may have a faulty reed switch for the appropriate direction that needs to be replaced.

The graph is wind direction, because the unit has since died I have dismantled it to find out how it works
It has disk with slots in it which covers and uncovers light sensitive diodes/resistors and gives 16 compass points.
I'm not sure if the issue is wrap around or that both the top and bottom of wind display graph is north.