without prior notice; without warning
Used when something happens suddenly, without any advance notification. Often appears in formal or written contexts, such as service changes, cancellations, or unexpected events.
The event may be canceled without prior notice.
Specifications may change without notice.
いきなり is casual and implies something happening out of the blue, often with a nuance of surprise or rudeness, whereas 予告なく is more neutral and formal.
Standard kanji-kana spelling.
Kanji spelling using 無く; less common but still seen.
Compound of 予告 (advance notice) + なく (adverbial form of ない, 'without').