The chances are, no one truly knows when Adele's new album is due, except for Adele and her label. However, Hits Daily Double seems to think that her album will be out "in the second half of 2015." Then the second half will come round and no sign of the album, so the estimations will just get easier and everyone will be able to work out that the release will coincide just in time for (Adele's favourite colour) Black Friday.
