My bike lived for 2 years outside in a UK seaside town, 1 mile from the sea. Every night I would ride along the seafront, whatever the weather. During storms I would catch a lot of sea spray. The steel bike is still going strong.
You need to rustproof the inside of the frame, with framesaver wax (or wd40), and protect the outside with a car wax. I also use wax to protect cables and the exposed section of bottom bracket, which can pick up a lot of rust.