no native english speaker here, but i guess
"a whole 'nother" would be correct. but let people be lazy when typing online.
actually i guess you'd also need to switch the words to be gramatically correct: "another whole year"
native english speaker here, and I grant that english is flexible enough that such things are largely a matter of opinion, but "nother" bugs me. I would write 'other with the apostrophe used to indicate the mixing of "a whole other" and "another" into 'other. I would pronounce it "other" if I was thinking, but possibly "nother" if I was being sloppy.
I never thought about this until now, but I think this is a case of an interfix. So, it is turning "another" in to "a-whole-nother" much like "abso-f*ing-lutely" or "legend-and-I-hope-you're-not-lactose-intolerant-because-the-second-half-of-that-word-is-DAIRY!"
> I cringe when I hear people say this. It works in speech to the extent that "irregardless" or "I could care less" are acceptable.
I'm not sure where you're from, but in Yorkshire you'd end up saying such things yourself before long. What matters is comprehension, and whilst writing to an audience means you need to ensure clarity, the same concerns are less applicable to chatting to a lifelong friend.