Three types of climate with lots of hills and mountains.
A map of Horizon Zero Dawn has surfaced on NeoGAF . Looks like the game will feature three distinct geographic regions - a desert, snowy and green environment. A number of creatures that populate this terrain have been revealed recently.
With no real frame of reference it is hard to say how vast the map will actually be. A good point to start an investigation would be a comparison of the settlements seen in the trailers so far, but with no names to go on, it is a tricky endeavour.
The PlayStation 4 exclusive is set to release in two short weeks, on 28 February 2017, so we will find out soon enough.