Keep in mind that this material isn’t a quick fix. In order to get a truly accurate sky inside Unreal you need a multilayer solution. The three most important factors that contribute to the overall look of a sky are in my opinion exposure, scene color, and white balance. If you can get these 3 things and the sky material correct, you will be in good shape.

Ground

The ground started from an awesome Gumroad tutorial video I watched a while back by Aaron Kaminer. He breaks down this shader in a way that’s easy to understand and shows you how to make it parameterized. You can find it here.

I made a few changes to the material, mainly altering the textures/roughness to be much more wet and muddy. From here, I just applied the material to a ground plane and used the mesh paint tool to paint in my puddles! I used a high poly plane for this and utilized tessellation. This material is designed around using heightmaps so tessellation is key here.