Funny, the weather bit is also true of us Germans. Even our saying is almost the same. "Es gibt kein schlechtes Wetter, nur schlechte Kleidung." And we also have this one: "Wir sind ja nicht aus Zucker." (We're not made of sugar.)
I'd heard "There's no bad weather, only bad clothing" growing up in a USA state with a high number of German, Dutch, and Finnish immigrants. We also played outside unsupervised a lot 30 years ago (but we also played a lot of video games). I don't think the children where I grew up are still playing outside unsupervised -- I believe it's not entirely legal anymore.