The standards for siting a station are to have temperature sensors 4 to 6 feet (1.2 to 2.0 meters) above the surface, and 30 feet (9.1 meters) for wind.
Photo by Ed Heaton, Chester County, PA
Photo by Grant Burgess, Greta, Australia
But there is more to consider than just height. An anemometer at 33 feet (10.1 meters) in the narrow alley between two 100-foot (30.5-meter) buildings and a temp sensor exactly 5 feet (1.5 meters) above a large black asphalt parking lot will not give you very usable data. But, what if what you want to know is how hot it gets in the parking lot, or how fast the wind whistles down that urban canyon? The point is, you want data that pertains to your specific needs and environment.
Siting standards are guidelines that most users probably can't meet perfectly. You want to mount your weather station as close to the standards as possible, but odds are, you won't be able to find the perfect site.
For those who require more precise siting, a Vantage Pro2 is the station for you, because the anemometer can be mounted on the roof or a tower, and the rest of the sensors at 6 feet (1.8 meters).
In the case of Vantage Vue, the two sensors cannot be separated, so they must be mounted at the same height. A compromise would work, but perhaps a better way to look at it would be to consider which information is most important to you. If you live where wind is the most interesting weather variable and you have many trees sheltering your yard, mounting on the roof, 6 feet (1.8 meters) above the surface, will be the best option. (But bear in mind that you will need to access your station for routine maintenance.) If you really are more interested in rain and temp, then finding a spot where the station can be mounted at 5 to 6 feet (1.5 to 1.8 meters) will give you accurate readings for temp and rain and will allow easy maintenance. (Bear in mind that wind readings will be affected by obstructions on the ground.)