。
What's the weather going to be like tomorrow?
Literal
Tomorrow [possessive-の] weather [topic-は] how [polite-です] [question-か].
A beginner-level question using the どう ('how') question word with です and the question particle か. どうですか is the workhorse 'how is X?' pattern — used for asking about weather, taste, health, opinions, and anything else. The polite か is usually softened in speech to rising intonation, but written form keeps the か.