Given:
$\sim( p \leftrightarrow (q \vee r) )$
$p:$ It's raining
$q:$ The sun is shining
$r:$ There are clouds in the sky.
Translate the proposition into spoken language.
Solution:
It's false that it's raining if and only if the sun is shining or there are clouds in the sky.
Would the solution above be okay?
$\sim(A\leftrightarrow B)\equiv (A\leftrightarrow \sim B)$.
So $\sim(p\leftrightarrow(q\vee r)\equiv p\leftrightarrow (\sim q \wedge \sim r)$
So I'd suggest: It's raining if and only if the sun is not shining and there are no clouds in the sky.
[I wonder if your $r$ should be 'there are no clouds in the sky'. That would make more sense.]