premonition (that something is going to occur) n.: presentiment

[Usage note: Presentiment often, but not necessarily, refers to a premonition that something bad is going to occur.] ❚ The feeling that something could go wrong [when the date becomes January 1, 2000] turns out to be hard to shake. … You can’t criticize the decision to stay on the safe side. Who knows what lunatic or team of lunatics might turn a presentiment of doom into an active effort to usher it in? Maybe, just maybe, tonight will bring chaos. (Amy Schwartz, New-Year Fears, The Washington Post, 12/31/1999.)

This word, when used in the above sense, can also be a synonym for anticipation, apprehension, fear, feeling, foreboding or hunch.