What is the ruling on saying, "I am sure that such and such will happen," based on data and experience?

What will happen in the future is considered part of the knowledge of the unseen, which no one knows except Allah. No one is permitted to claim knowledge of it. However, it is not claiming knowledge of the unseen for a person to anticipate certain outcomes based on their experience, the repetition of an event, or to expect what has been supported by evidence.