gpedro developed a nice plugin which adds snow effect on the website.
The plugin works only in december, but this can be changed by editing the plugins/myaac_snow_december/myaac_snow_december.php file and removing following 2 lines:
if (date('m') === '12') {
}
Plugin can be downloaded here: https://github.com/gpedro/myaac_snow_december/releases
Demo: https://demo.my-aac.org/