Hi!
I needed some rain and snow in a project and decided to share the results. You can add the effects to a scene by using the plug-in, but beware that you can only have one particle layer at a time (at least for now, or use the script that Svarov wrote). If you want snow and rain at the same time then you have to render one effect with a transparent bg, delete it from your scene, and then add the second effect to your scene and compose them in an editing program.
Greetz!
edit:playing with particle smoke layer.
add-snow-particle-layer.zip (8.79 KB)
add-rain-particle-layer.zip (9.02 KB)