@malikdiallo Hi! Your questions really peaked my interest! So I asked Koro, a friend of mine, about them. She said:
I face this question all the time.
Waati is weather, but can’t translate directly. Only contextual.
These are two ways she shared:
Nin yɔrɔ cɛ ka ɲi = This place is nice
Bi fiɲɛ ka di = Today the air is pleasant
‘Yɔrɔ’ seems to be the most common way to describe weather though, as you and @coleman have also used it here. But I have to admit, I like “Bi fiɲɛ ka di” better!