Outdoor Research Seattle Rain Cap – Waterproof & Sun Protected Baseball Cap

I wear a size 8 do you think this hat would be comfortable enough to wear or two small?

I'm a senior & can't afford this high cost. Need a waterproof rain cap like this. Any product recommendations that are less expensive?

I have an OR cap already and it gets blown off all the time, is this wind proof too?

Is the brim Goretex? I want the brim to be waterproof, not just the crown