[verb (plain)] + くせに [i-adj] + くせに [na-adj] + な + くせに [noun] + の + くせに
くせに means "even though", and it complains: someone does something they have no business doing, given what they are or what they know. It follows a verb or an い-adjective in the plain form; a な-adjective takes な and a noun takes の.
A noun takes の, a な-adjective takes な: ×子供なくせに, ×暇のくせに.
For the same reason, both halves of a くせに sentence are about the same person, whose behaviour you're criticising. Weather and things that just happen take のに.
These go beyond criticising someone else in mid-sentence.
Turned on yourself, くせに is self-reproach.
The sentence can stop at くせに and leave the complaint unsaid.