So I went out this morning and checked it visually. The wind was out of the south-west. Checked the screen. South-east. D'OH!
So it was BACK up onto the roof, drag the ladder up there again, balance myself on it while reaching up above my head to loosen the nuts, turn the unit over so the vane is on top instead of the anemometer, and reattach it to the antenna mast.
I also took the opportunity to adjust the angle of the solar panels to a more efficient position. I should also probably reposition the solar panels for the themo-hygrometer. The current location is fine for the summer, but the sun is further into the southern sky in the winter, so the panels should be moved to the other side of the patio.
I found some 2x4's on the back porch. I need to see if I can use them to build a base for the rain gauge. I'm probably going to bolt it to the patio roof, since I really don't want to screw anything into the roof of the house.