The idiom ‘bolt from the blue’ is used in English to describe something unexpected and sudden. It originated from the notion of a thunderbolt, which is often accompanied by lightning during a thunderstorm. The ‘blue’ in the expression refers to the blue sky, as thunder and lightning are not typically associated with clear, blue skies. When something comes as a ‘bolt from the blue’, it means that it was totally unexpected. For example, the news of a sudden marriage proposal or a surprising event can be described as a ‘bolt from the blue’. The expression is commonly used in informal contexts and signifies a sudden and unexpected occurrence.
