"Imminent" means that something is just about to happen, and it could happen at any moment. So, for a hurricane, it is imminent to a certain location if the winds will be dangerously high VERY SOON. It could be minutes, or even hours, and the time is not predefined.
"Imminent" does not mean that it will definitely happen. I'm sure you've seen movies where clock attached to a bomb is ticking to zero. Explosion is imminent! However, if the bomb squad defuses it with 2 seconds left, the explosion doesn't happen, even though it was imminent.