I've left my bikes out a number of times.
Once it had punctures in both tyres; someone left nails in the tyres to show they did not want the bike there.
Another time I found it with a note saying it's blocking the pavement (yet it was less of an intrusion that the cars parked on the pavement.
Yet another time I found it with crisp packets, soda drink cans, various coffee cups and chocolate wrappers inserted into the wheel spokes, the rack, the bottle cages etc.
Twice stolen.
I leave my two main bikes out all the time regardless of weather though I might put them away if I've just cleaned them and it's due to rain later that night. Or not. Some years ago when it snowed really heavily for a few days, I left the bike out and it had a bunch of snow piled onto it (I had no idea a skinny bike frames could gather up so much snow). The brakes worked ok but the gears didnt change well until about 20 minutes into the ride when things had warmed up (can't explain why the brakes still worked though, kind of).
My SO left her bike out, properly covered, and when she next went to use it, the chain was tad rusty. Unsure why. It was a new bike and I had not applied any lube to it so it had whatever lube it came with (which IMO is supposed to be pretty good stuff). Anyway, it's never rusted after I lubed it up.