What is rhe importance of the first scene to the play

Literally, the first scene is meant to send a shiver down the backs of the Elizabethan audience. They really believed in dark magic, witches, the Devil.....The scene sets the tone for the whole play. Macbeth (the play) always flirts with darkness and tragedy. The stormy weather combined with the witches nasty spells serve as an ominous harbinger or prelude to the wicked deeds that are yet to come, specifically by Macbeth.