Abandoned bikes

Here you have some more pictures, you can even see that someone had a go with a hacksaw some time ago and that had rusted too! but yes...maybe the level of humidity raised to 600% in two days and all that rust just appeared overnight...

That only confirms this...

...it looks more likely that it was attempted stolen pre-Christmas

And I can tell you know nothing about rust, it's not time that is the issue it's evaporation and salt. Given that it has snowed several times, melted during the day, and that salt has been sprayed... honestly, that level of rust is expected from any bike that has been locked outside for the last month.

Not months, or years, but month.

Hell, the chain on my road bike that has spent 60 days on my balcony is as rusty. And that hasn't even been near road grit/salt.