Does high blood pressure cause migranes?

Yes it may. Migraine and hypertension are common conditions that frequently coexist. The relastionship between the two is usually coincidental, but some evidence suggests that poor control of blood pressure may exacerbate the frequency and severity of migraine.
Uncontrolled HTN. Uncontrolled hypertension can cause a vascular headache, but mildly elevated hypertension does not trigger a migraine.