In Act I, scene 2, the Soothsays warns Caesar to beware the Ides of March.
The next indication of the supernatural and bad omens can found be found in Act I, scene 3 between Casca and Circero. It is a night filled with thundering and lightening, never a good sign. First, Casca talks about the violent weather before telling his friend about a slave whose left hand flamed like a torch yet his hand remained unscathed. He continued to speak (lines 15-32) of other unusual happening like an owl in the market place at noon. He concludes by saying that all of these things portend more of the same.
In Act II, scene 2 Caesar also speaks about the weather and how his wife had nightmares about him being murdered. Calpurnia herself pleads with her husband to stay safely at home since she too, has heard of strange and unusual things happening. Finally Caesar yeilds to his wife for not for long.
Decius explains away Calpurnia's fears.
Despite by all the signs and supernatural events and the Soothsayer warning, Caesar follows the men to the Senate and his death. He lets his vanity win out over everything else. He even mocks the Soothsayer when the man again warns him to beware the Ides of March. Caesar says he isn't worried since it has come and he is still alive. The Soothsayer reninds him that yes the Ides of March have come but not gone. Caesar doesn't listen.
In Act III, scene 3, Artemidorus also trys to warn him of the plot against him but Caesar dismisses him.
Caesar's pride, his feeling of invicibility lead him to his death.