The sale will begin from the 22nd of December, which is today, and will last until the 3rd of January, 2017. This means that you’ve got about 2 weeks worth of sales to look forward to. Just like with other Steam sales, the discounts and the various deals will change as the sales progress, so what you see today might be different tomorrow.
There are a bunch of games that have been discounted, and at a quick glance it looks like some of the discounts are pretty generous. For example the Enhanced Edition of Baldur’s Gate has been discounted by 60%, and some titles like Insurgency have been given a whopping 80% off. Granted there are some that are only seeing a 10% discount, but hey, better than nothing, right?
In any case you’ll have a couple of weeks to peruse the various titles on sale but like we said, the sales will come to an end on the 3rd of January so you’ll want to take note of that.