Premonitory (adjective)

1. Serving as a warning or indication of something to come.
2. Providing advance warning of a future event or situation.
3. Serving as an omen or a forewarning of something.

Origin:

Late 16th century: from french prémonitoire or latin praemonitorius, from praemonēre 'warn beforehand'.

Examples:

1. The headache was a premonitory symptom of the impending migraine.
2. The earthquake was a premonitory sign of the volcanic eruption.
3. The dream was a premonitory vision of the future.
4. The premonitory signs of a market crash were ignored by many investors.
5. The premonitory feeling in the pit of her stomach told her that something was wrong.