Tower Controller providing visual separation during opposite direction landing and departing traffic indicated that post flight communications indicated the landing traffic encountered IMC conditions; the reporter noting never losing sight of both aircraft.

Narrative

A CRJ7 was departing on a SID with traffic in opposite direction [on] final; call sign and aircraft type unknown. I was providing visual separation between the two aircraft. Traffic was exchanged multiple times. I believe the aircraft on final had the CRJ in sight. The CRJ started the westbound turn required by the SID out of 9;600 FT MSL instead of 9;100 FT MSL that the departure procedure calls for (not uncommon for pilots to do); putting the aircraft behind the aircraft on final. The pilot of the CRJ later called the Tower and said that they never did get the airport in sight and that they had to fly into clouds to avoid traffic. I had both aircraft in sight and did not observe the CRJ flying into clouds. The pilot never said anything during the operation. Opposite direction traffic at ZZZ is an operation that puts aircraft in close proximity with each other. More traffic could have been exchanged. If the Tower is providing visual separation between arrivals and departures; to ensure separation; aircraft are instructed to stay on the 340 heading and not start their turn if an aircraft on final is not descending quickly enough. I think that this is the only logical way to run the operation in ZZZ. I do not believe that the situation was out of the 'norm' for this airport.