Being this a phenomenon both unexpected and startling, in the figurative sense it indicates an event which is a complete surprise

He was sure of being reelected as mayor, but the charge against him for embezzlement came like a bolt out of the blue in the middle of his campaign and he had to step down

Era già sicuro di venire rieletto sindaco quando, come un fulmine a ciel sereno, è stato raggiunto da un mandato di cattura per peculato nel bel mezzo della campagna elettorale e ha dovuto ritirarsi

The decision of the great tennis player to withdraw from the tournament on the eve of the final, came like a bolt from the blue and left everyone confused

La decisione del fortissimo tennista di dare forfeit il giorno prima della finale del torneo, è arrivata come un fulmine a ciel sereno lasciando tutti increduli