I've always thought of summer and winter hats separately. I'm not sure which we're discussing.
In summer, I wear cotton caps. Mine, as in my previous post, are custom made on the large side, but just the cotton racing caps that cyclists wore for decades. In winter, a peaked winter cap, again a pretty traditional choice, or quite often just a beanie-style hat, often from a camping shop or similar. A peak can be helpful in rain, as I wear glasses, but I manage.
I've not worried about the hat being waterproof. I find that any hat helps. I was out like that on the Tribute Audaxes from Reading a month ago - I gather that was the wettest day since records began? That hat was the kind that's made either to go under a helmet or to wear on its own. But I might have done better to wear a peaked one that day!
