Lightweight Dress Shirts for Boys 8-20

I live in Tucson, Arizona. The temperature is starting to rise and in the mid summer it will be over 100 degrees Fahrenheit.

I’m looking for a company that is selling lightweight dress shirts. I already buy from Zara, but I’m growing out of their boys section. I’m 14 years old so US sizes would be 16 and UK goes by age.

Thanks a lot. Any ideas would be very helpful.