Zima zawsze nachodzi, Bran.
Almost. It's "nadchodzi". "Nachodzi" (na coś) means that it overlaps with (on) something :)
"Nachodzić" also means to pester or to intrude and it was the first meaning that popped into my head when I had read that word.
"Winter is over?"
Well, not yet. It's close to the end, it's 'in the process of ending', but not over yet.
The winter is ending is also correct. Duo doesnt agree.
Added "the", will work now.
"Winter is finishing"?
Why not zima kończy się?
We should avoid putting a pronoun (and "się" is a pronoun) at the end of the sentence if possible.