Yes having dizziness can be a sign that a stroke could be coming on but usually you'll have other signs of a stroke before the stroke actually happens.
Other signs and symptoms of a stroke are Weakness or numbness in your arms, face and legs, trouble understanding or confusion, vision problems in one or both eyes, loss of balance, trouble walking, loss of coordination and severe or sudden headaches without any obvious cause.
If you think you or someone is having a stroke call 911 right away because a stroke is a very serious matter.