It said I was wrong for saying "Today it is a sunny day"... seems harsh? :-P
Duolingo should have given the word, ensolarado, in a previous lesson before expecting students to know its translation.
Apparently Duo's having trouble recognizing that ['s] after a noun in English can mean possession AND a contraction of NOUN+is. I'm gonna keep reporting it until this problem is fixed.
IS Hoje é ensolorado also ok?
You can say "Hoje está ensolarado".