A snow effect realized using three.js with a fallback using CanvasRenderer. It should work on most devices.
You can see the result here: http://nicolas-van.github.io/snoweffect/
If you want you can directly use this animation on any web page by using adding this code in it:
<script src="https://cdn.rawgit.com/nicolas-van/snoweffect/gh-pages/static/all.js"></script>