Windy days DEFINITELY frizz out my hair. I went out one day when it was very windy to walk the dog. I left with beautiful chunky curls and came home with a rat's nest of unruly, frizzy, poofy, straighter hair. For me, the wind is most definitely worse than humidity. It's not even that it gives me an unbearable amount of frizz, although it does give me some. It's more that it separates any and all my clumps, gives my hair more incentive to poof, and tangles my hair like it's nobody's business!