Which of these sentences are correct?
i think both, it depends on what you actually wanna express, but grammatically both are correct. But wait and see, a native speaker’s opinion about it
Both are correct and the difference in meaning isn’t great:
It’s getting colder means that versus some comparison period (five minutes ago or yesterday) the temperature has dropped. What is the comparison period? We know that from the rest of the conversation – or we just know that it was “recent.”
It’s getting cold means that compared to some standard of comfort (like being outside wearing shorts) the temperature is too low. It’s getting cold outside, better bundle up (wear a coat).