OK now. I fish 3-4 times per week from Late April into late November. Most of my fishing is afloat on a flat or inshore, casting for Stripers. Until last year, my goto fly for windy days was a sparsly tied Deceiver. Last year, I chucked a lot of Skok mushy-type flies made of angel hair, mega mushy stuf, etc. Where the biggest deceiver that I found comfortable to cast on windy days was probably a full 6 or 7 inches, the Skok type flies add and inch or two to that.

I want a big fly that can imitate a Pogy or Herring. Presents a big profile in the water. Casts well in the wind. Relatively easy to tie.

What do you use for big flies on days when the wind gusts up to 25 MPH ?

Use the same patterns, just add some lead to them. You need some weight to combat the air resistance of the bigger flies.

You can also use the same flies tied a bit bigger with a heavier flyline / flyrod.

I like a hollow fly tied with Farrar fiber. Very sparse, almost no weight at all. Big profile.

I use a EP Herring fly . The EP fibers are very light and shed water. Buffy is also a good fly and long with the Mega Mushy. The key is in the casting. Your timing must be right to cast these large patterns. Consider a spey rod for the big flies. FishHawk

I use big (BIG) flat wings... If you ty them with several hackles in the tail and flare the bucktail they really have a great profile in the water andlook everybit alive. When you lift them off the water they have very little wind resistance. I regularly cast flys 14 inches some itmes with dropers with an 8 weight rod. Tie one on and give it a try!