Several manufacturers make connectors for UF cable. They may be hard to find at the wholesale house because they so rarely sold. Also, most folks don't care to pay the price for them.
Arlington Industires is one manufacturer that I know of. I don't have a web address for them, (800) 233-4717
You are probably correct in thinking that a standard Romex connector is not Ok in a wet location. The UL White books says they can be used with UF cable in dry locations unless otherwise indicated on the carton.
Few things are harder to put up with than the annoyance of a good example.
Re: NMC Connectors for wet location#79692 01/12/0210:28 AM01/12/0210:28 AM
GENERAL — Connectors "Listed" for use with nonmetallic sheathed cable are also suitable for use with multi-conductor underground feeder and branch circuit cable where used in "dry locations" unless otherwise indicated on the carton.
See the Definition of Location in Article 100:
Joe Tedesco, NEC Consultant
Re: NMC Connectors for wet location#79693 01/12/0211:05 PM01/12/0211:05 PM
Sparky, I said "last I remember" ya know how long it's been since I've been in business ? However, I did catch a contractor about to use regular romex connectors in a damp location, he did not get to , but the connectors he bought were T&B again, not SURE of the number.
Re: NMC Connectors for wet location#79698 01/13/0202:32 AM01/13/0202:32 AM