In this selection, the sentence seems to be using "the wind was our friend on the way back, though." as an indication that the wind might most likely not nearly as bad as it was when they started to go for a skate. Short explanation: It wasn't as bad as when they first started.
The whole To Kill A Mockingbird was told from a point of view when Scout was grown up so she realized then, but as a child she was innocent so she did not realize that they was a mob in the first place. So for a short answer No she was aware.
