Snowfall will include:
Now is the Winter of This Content: Rain and fog for existing maps, plus a new “Winter” map theme with snow and all of its challenges.
The Streetcars You Desire: Expanded public transportation options, including easier management of existing lines – and Trams, a new system demanded by fans.
World Warmth, Too: Cold weather increases demands for electricity, unless new water-based heat systems are in place.
Plowers to the People: Build a snowplow depot to keep traffic flowing during winter weather, and employ new road maintenance systems to keep your streets in shape.
And here is the trailer
No news on pricing, and with the release date all they have said is later in the year
My own thoughts: It is good to see that Cities: Skyline takes over where Sim city failed and they have done a very good job so far but i do hope they continue to support the game with more content.