There have been speculations that "The Winds of Winter" might be released prior to the premiere of "Game of Thrones" season 6. The HBO adaptation of George R. R. Martin's "A Song of Ice and Fire" saga regularly premieres around April and season 6 is likely to start airing around the same time next year. Thus, if Martin will have the sixth book published prior to the season's premiere, then it just might hit the shelves by February to March of 2016, or even earlier. 

Perhaps, another clue can be gleaned from the 2016 Hugo Awards. According to a report from the Latin Times, novels for the Hugo Awards should have been published the year prior, and the only way for "The Winds of Winter" to be included in next year's awards is for it to be published before 2015 is over. The report states, however, that Martin may still get the book published in time for it to be eligible for the awards. 

Martin did note on his June 10 post on his personal blog, "Not a Blog," that he would be attending and voting in this year's Hugo Awards. The author has been an active attendee of major book ceremonies although he did confirm earlier this year that he is skipping out on this year's San Diego Comic-Con and the World Fantasy Convention in order to focus entirely on finishing the book. 

In Martin's blog post, he also expresses the difficulty in finishing "The Winds of Winter" due to a very busy schedule. The author is writing the book while also working on three different concepts for HBO and Cinemax, which includes the previously reported "Captain Cosmo" series. He also explained that he will be busy traveling throughout 2015. 

[Spoiler Warning] "The Winds of Winter" will continue several loose plot threads left in book 5, "A Dance with Dragons," such as Jon Snow's fate, Cersei's trial by combat, Daenerys' confrontation with Khal Jhaqo, and Tyrion's campaign with Aegon Targaryen in the Storm Lands.

For now, there is still no confirmation on when the novel will be published.