what kind of hat would be most effective for reducing heat?

Panama Hats is known for being breathable, light and durable while providing a decent shade. Despite the name, Panama Hats are from Ecuador but became widely popular in Panama and used all around the Caribbean.

Real Panama hats are available here in Ecuador for as little as $15 USD but are sold in many airports around the Americas for about $45. They last quite a long time and have the nice property that they do keep their shape after being rolled and unrolled.

Recently I had one last for 80 days of daily use around the world, including these:

• the Dubai (UAE) where it reached a dry 42C
• Vietnam where it exceeded 38C with high humidity.

When in the shade, I took it off to let the breeze dry my hair since one eventually is going to sweat no matter what.

Colombia makes cheap knocks-off, available for around $6 USD which are pretty good at providing a bit of shade but do not last long at all. The one I bought there got completely destroyed in 4 days. Still, as a disposable expense, it was worth it. The difference is the straw used which is brittle and breaks.

I like a Jackaroo. With the screen wire. Australian made hat. Not cheap. Philippines. Like a western cowboy hat wide brim. You can wet them down. 2nd place. While in America I found some hats at W Mart. Screen wire in them round wide brim. The head band held them a little out from the head. Canvas material. You could wet down. Made in China. 3rd your old stile straw hats. Non coated just wove. You can wet them also. Do not last long. But are very cheap native made hats. 4 Your Vietnam stile reed cone hats. Noncoated dampen down. The thing is venting the hat & can it take being wet down. Not looks or cost. If out & about. Ball caps closed hats are the worst. So wide brim vented hats. I picked up some very cheap wove cloth derbies at UniTop a while back, Worked well but fell apart fast in use. With no liner in them.