How do you say it is a magnificent day in French?

There are several ways to say "it is a magnificent day" in French, depending on the specific nuance you want to convey:

Formal:

* C'est une journée magnifique. (This is a magnificent day.)

* Le temps est magnifique aujourd'hui. (The weather is magnificent today.)

Informal:

* Quelle magnifique journée! (What a magnificent day!)

* C'est une super journée! (It's a super day!)

* On a une journée magnifique. (We have a magnificent day.)

More poetic:

* C'est un jour splendide. (It's a splendid day.)

* Le ciel est d'une beauté rare aujourd'hui. (The sky is of rare beauty today.)

Ultimately, the best translation will depend on the context and your desired level of formality.