Steam Next Sale Countdown

How does it work?
Valve never announces Steam sale dates up front, but Steam sales return every year in a relatively stable frequency.
Based on data from the last few years, the upcoming sale dates are predicted.
These predictions are a combination of the following factors:

GET notification as remainder
Dates and months in which a sales started
Which day of the week a sale usually starts
How long a sale usually lasts
What dates/events a sale generally hits
Times are based on the East Pacific time zone
Furthermore the dates are updated every now and then when there is more information in recent news.
As you can see there are multiple sources to find out when a sale will most likely start.