Translation:How strong is the wind?
Depends on what you want to say, and how formally you want to say it. "風はあまり強くないです。" = "かぜはあまりつよくないです。" = "kaze ha amari tsuyokunai desu." = "The wind is not very strong."
If you want to talk less formally you could answer: "めっちゃ強くだ" = "めっちゃつよくだ" = "meccha tsuyoku da" = "It's very strong!" The second example uses a regional word "meccha" which means "very." In more natural conversations the topic word is understood and doesn't have to be repeated until the topic is changed. "da" = informal way to say "desu"
It isn't grammatically correct
In English you can't end a sentence with a copula, it is a linking verb that goes between the subject and complement. "How strong is the wind" "The wind is strong"
"Oh my; how strong the wind is!" can be a very antiquated way to remark on how the wind is strong but it is never read as a question