Headaches in the sun can have various causes, ranging in severity from 'very minor' to 'worrying'. Finding the true cause means ruling out or confirming each possibility – in other words, diagnosis.
Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms. In order to diagnose headaches in the sun, we could:
Do you get headaches when hot or out in the sun?
Possible responses:→ No / don't know
→ Occasionally / moderate
→ Often / severe