a bolt from the blue
US /ə boʊlt frəm ðə bluː/
UK /ə boʊlt frəm ðə bluː/

1.
un fulmine a ciel sereno, un evento inaspettato
a sudden, unexpected event that is usually unpleasant
:
•
The news of his resignation came as a bolt from the blue.
La notizia delle sue dimissioni è arrivata come un fulmine a ciel sereno.
•
Her sudden illness was a bolt from the blue for the whole family.
La sua improvvisa malattia fu un fulmine a ciel sereno per tutta la famiglia.