what an attic fan is and its purpose.

An attic fan reduces the super-heated air in the attic by creating outside circulation through the attic. It does not circulate, nor remove air from the living areas of the house.

I put an attic fan in before we had AC and it significantly helped reduce the heat passing through the ceiling into the living areas. Additional insulation is also something to consider if what you have is below standard and that means the typical R-19 is about half of what you should have in the attic.

Also the OP had concern about putting a fan through the roof. I installed my fan in a gable end and made sure there were adequate air vent entrances in the other gable ends and/or the eaves. If you have a hip roof, this obviously won't work and you will need to put the fan on top.