"Is the wind strong?"
No, as は is the marker for the "topic" of a sentence. が is the marker for the "subject" of a sentence. This is really just one of those things that you have to simply learn to distinguish between with exposure to Japanese, since in English, we don't make this distinction. Generally, は is used for an idea that both speakers already know about. が is used for a new idea, like one from your own head, such as expressing likes/dislikes. There's also a variety of differences between them, but that one seems like the most relevant to this sentence.
So, in this case, かぜ is something already established. We already know what "the wind" is in this sentence. So, therefore, it is correct to use は here rather than が.
If you say 風は強いですか? you are asking if the wind is strong. If you say風が強いですか? It sounds like you are talking to someone, they said something was strong but you are not sure what they said. You think they said the wind so you say 風が強いですか? Is the wind, you said that was stong?