To ensure effective measurement with your FieldKit Weather station, your sensor cluster should ideally be a minimum of five meters (15 feet) off the ground to avoid boundary layer effects. If you are using a solar panel, you should ensure that it receives 6-8 hours of full sun each day, and it should be pointed in the compass heading appropriate with the location. Additionally, make sure everything is tightened down and secure, especially if you may experience intense winds.
Check out this blog post walking you through an example FieldKit Weather installation.