Over six seasons, we've had ample warning about the fact that 'winter is coming'. At the end of the latest season, winter actually arrived but, unfortunately, our real life weather isn't quite ready to cooperate. As David Benioff and D. B. Weiss explained in an appearance on the UFC Unfiltered podcast:
"We don’t have an air date yet, but this year will probably be a bit later. We’re starting a bit later because at the end of this season, winter is here. And that means that sunny weather doesn’t really serve our purposes any more.
So we’ve kind of pushed everything down the line, so we could get some grim, grey weather even in the sunnier places that we shoot."
And that's bad news for impatient fans as even postponing filming by a few weeks could lead to air date delays. Traditionally, Game of Thrones returns to screens around March/April time. So while winter has finally come to Westeros, we might not be able to see it until summer 2017.