By far the most common cause of failure in trees is loading due to strong wind action during storm events. Since wind can cause much larger bending moments in trees than, for example, a static load from to snow or ice, due to the predominant loading direction perpendicular to the trunk axis, the estimation of the wind load is of particular importance in a safety assessment.

The wind load acting on the tree is determined both by the wind speed and gust structure of the wind at the site and by certain tree characteristics.