Hurricanes have been rated category 1, category 2, etc., up to category 5.
Now, since we have had a greater frequency of category 5 storms, not all of them are the same size. So meteorologists are considering starting a new rating system, one that allows for category 6 or whatever.
When God gives us natural disasters like that, it is not His justice but He is granting us His mercy, to remind us of our need for repentance, before it's too late.