I live in South Florida and in summer it gets hot.  This hat keeps the sun off while the ventilation keeps it cool inside. The snap up sides and chin strap help deal with wind. This hat is of good quality and nice design.

Update: After using it for awhile I noticed that it tends to stain from perspiration. You have to wash it often to prevent this.

Update: After four years of daily use my Tilly has gotten some permanent sweat stains and the material is beginning to fray. That will give you an idea of its expected life. I send it back to the company and they replaced it. They honor their guarantee.