Could you edit the .json file and confirm it parses correctly?
Judging from the output this looks like a list of lists. The last snippet is malformed, also. Should be
list(id = 800, main = "Clear", description = "sky is clear", icon = "01n")
The general outline of the approach is given in this post. In the terms discussed there, x is jsonData, y is possibly a data frame with columns id, main, description and icon. f is the function (probably composite) to be applied to x to get there.