Thank you for your question.  Could you please provide your location, as well as the temperatures this summer?  If this is a fungus present in your area, the spots would have tobe examined by a local lab or horticultural service.  Have you observed the spots before?  Are just the leaves facing the sun spotted, or does it occur over the entire plant?  Thank you for more information.

All of the leaves that have spots are part of external layer. All inner leaves are safe, and have no spots. Do you see the spots like those invaded by bacteria or these are just sunscalds?
my tree is facing a 6 hour direct sunlight.

The average temperature was 30 degrees Celsius.

What is your location?

W Virginia 

Your question indicates you are from Outside United States.  What county in W. Virginia?

Wayne county

It doesn't look fungal to me. I'd go with sunburn.