Talking about the temperature

Question

Is it correct this? :

Today is 25°C

Or this:

Today it’s 25°C

And without today:

Is 25°C/ It’s 25°C

Answer 1

In common usage, it would be more correct to say, "It is 25°C."

In this context, the "it" is generally understood to mean to "the temperature".

For example:

Today, it's 25°C.

Today, the temperature is 25°C.