It's possible to use the popular UDS plugin with Ultra dynamic weather. This adds a sophisticated sky and lighting system, as well as material effects on the landscape material. This even works with RVT as the dynamic weather material effects can be layered over the top of the virtual texture.
To add UDW simply add Ultra dynamic Sky to your project. Then go to Content/Brushify/Materials/Landscape/M_Landscape and open that. Zoom in on the far right and find the Runtime Virtual Texture section.
Find the MF_RVT_Landscape material function and double click it.
We're going to add the UDW function here.
Right click and Search for dynamic, you will find Dynamic Landscape Weather Effects. Add that node and connect the Dynamic Landscape Weather Effects like this:
Now hit compile and save. This will recompile shaders which may take a while.
Once that's done , add UDS and UDW blueprints to your scene as normal. You should can now set the presets for rain , snow etc. and you will see puddles and snow forming on the landscape:
If you want snow to form on objects, you'll need to go in and add the snow material function to there shader as well.
Additionally, if you aren't using RVT, you can setup the UDW without rvt like this:
