Do you have to add like what asking about the weather?

yes. Here like is used as a preposition, which means "like" Because what means "what", you must add "like" to express "what", so you must use like here. This is a fixed sentence pattern, What's the weather like today? What is the weather like today?

sentence patterns asking about the weather

What's the weather like in spring? What is the weather like in spring?

the sentence structure of asking about the weather is: What's the weather like＋+prepositional phrase indicating place or season?

This is a special question guided by what.

pay attention to add prepositions (such as in, at, etc.) before words indicating places or seasons.

the answer to this sentence pattern is usually: It's＋+adjectives indicating weather conditions.

For example:-what's the weather like in Harbin in winter? What's the weather like in Harbin in winter?

—It's very cold. It's very cold. Lexical analysis

1. like

Chinese definition: prep. Similar; Similar; Like; (asking for advice) How about ...; (of what someone often does) conforms to the characteristics of ... only like ...

Example: As soon as I know I'm in the team it's like I'm walking on the air.

When I learned that I joined this team, I was as happy as flying in the sky.

2. weather

Chinese interpretation: n. weather; Weather; Weather forecast

Example: I'm afraid you're running a risk setting sail in such a stormy weather.

I'm afraid it's too risky for you to sail in such a stormy weather!