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Tree leaves detach due to the growth of an abscission layer between the leaf stem and the tree. This blocks leaf veins and ensures that an open wound is not left when the leaf falls off.
The main factor driving leaf loss is the drop in light levels, the weather affects the intensity of the autumnal colours. Colours being more intense with bright warm days and cool nights. Another reason for leaf loss is to prevent dehydration when the tree cannot access water due to the ground freezing. This is why larches, a conifer, lose their needles over winter; larches grow further north than other conifers.
Potential wind weather has little or no effect on leaf loss. Many evergreen trees grow in the tropics and are seasonally exposed to tropical storms.
In autumn leaves do not degrade significantly on the tree and require several years action by bacteria and fungi to break down.