Why does my sun not cast shadows north at noon at different months.

[johngow]

I'm trying to provide shade on an outside covered area and am getting wildly different shadow directions at noon in different months.

I know length of shadow will be very different, but shouldn't the sun cast the shadows in nearly the same north direction at noon any time of the year.

I've entered the longitude and latitude and know which way is north, but shadows are all over the place.  

Can anyone help with this?