Does this mean an object or the weather?
Could be either.
The pronoun 'it' can mean any object being weather,animal,water or anything.
Can i say "Das ist kalt!"? They are interchangeable?
They are interchangeable?
They are not.
das (that) is used to talk about something new.
es (it) is used to talk about something you have spoken about before.
That said, Das ist kalt! (That is cold!) is also a grammatical sentence.
The system did not accept my correct answer
Can you show it to us, please?
If you have a screenshot showing the question and your rejected answer, please upload it to a website (such as imgur) and tell us the URL.
I rechecked this and believe what happened is I wrote in th translation instead of what I heard. Please accept my apologies . Tony