I used the original Outdoor Research Seattle Sombrero on trips to Alaska and coastal Quebec/New Brunswick/ Maine, as well as rainy day trips in California. The hat provided good coverage during a downpour. I was less satisfied with the hat brim when it was windy. It didn't take much wind to fold up the brim, letting the rain onto my face or ear. The Gore-Tex material was breathable in cooler temps, but too warm for me in temps over 75*F.
I have had better luck with a Tilley hat in a wide range of conditions. The cotton Tilley, treated with a DWR spray, does an admirable job shedding light and medium rain. Even after all day outdoors, the hat isn't too soggy. If it's really pouring, I switch to a hooded jacket and a baseball cap. The brim of the Tilley retains its shape in strong wind, e.g., in Patagonia.