OpenSceneryX

From the project page:

The OpenSceneryX project is a free to use library of scenery objects for X-Plane®. It is a collaborative effort by members of the X-Plane.org community, providing a good range of high quality scenery components for authors to use in their scenery packages. The library contains many pre-built 3d models including buildings, aircraft and vehicles as well as a large collection of ground markings, ground furniture, trees and plants.

OpenSceneryX 4.x has native support for Four Seasons. During the install process, just select Four Seasons.

From the OpenSceneryX documentation:

OpenSceneryX now exports seasonal regions compatible with core X-Plane, the Four Seasons plugin, the TerraMaxx plugin and the xAmbience plugin. Seasonal support is optional and can be chosen on install. Note that we only support seasons for library contributions that have seasonal alternatives.