Du jour au lendemain
[du zhoo ro la(n) deu meh(n)
from the day to the next day
The French expression du jour au lendemain
is figurative. To say that something happened du jour au lendemain
means that it happened suddenly, very quickly, and possibly unexpectedly, but probably not that it literally happened during a single night. That meaning of "overnight" is equivalent to pendant la nuit
Il est devenu célèbre du jour au lendemain.
He became famous overnight, Suddenly he was famous, He rocketed to fame.
Nous nous aimions et puis, du jour au lendemain, il m'a quittée.
We loved each other, and then suddenly / out of the blue he left me.