How to choose CSS colors according to local date?

I have define twelve colours in a CSS file, each one for a specific month.

$january-garnet: #7b3f41;
$february-amethyst: #8c667d;
$march-qquamarine: #63c3ce;
$april-diamond: #cfe4ee;
$may-emerald: #3b8272;
$june-pearl: #d1d2dc;
$july-ruby: #9b111e;
$august-peridot: #e6e200;
$september-sapphire: #297bc1;
$october-opal: #f6e5d8;
$november-topaz: #ecbf8a;
$december-turquoise: #7fb0b6;

Now I want to set the $accent-color as one of these values according to the current month. How can I do this?