B737-300
Flight Crew Last 90 Days 212; Flight Crew Type 5000
Situational Awareness; Distraction
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter
General None Reported / Taken
Human Factors
Arriving visual to [Runway] 19R using ILS; we were asked if we had traffic to follow; an A320; in sight.  We confirmed we did and we were cleared for the visual to [Runway] 19R. I initiated a base turn and began to configure calling for flaps 5 and landing gear down. As I began to turn final; ATC informed us that we were 90 KTS faster than the A320 which had slowed to final approach speed and was doing S-turns due to being high on the approach. I disconnected the autopilot which was just about to capture the localizer; squared the base again; and held altitude while continuing to configure. ATC told us there was no aircraft behind us and that we could continue through the final and turn back (to create space) if we wanted; which we did. While continuing to hold altitude; I called for final flaps and then turned back to intercept the final during which we encountered the wake from the A320. I called for the Before Landing Checklist; which we completed. When we landed; as I began to retract the flaps; I saw that they were at position 25. The cockpit lighting was set somewhat low and we were running the checklist in the turn right after the wake incident. Those things probably contributed to missing the fact that the flaps were only set to 25.
On landing rollout to [Runway] 19L; the First Officer brought to my attention that we had landed flaps 25. I was pilot not flying and he was pilot flying for the approach. During the arrival; we were outside a great deal; as another carrier's A320 had pressed the field and was doing S-turns in front of us as we were cleared the visual approach from a right base.Tower called 90 KTS overtake on the Airbus and we were vectored across final. We hit wake turbulence from the Airbus; but did not upset. The First Officer was calling flaps and gear to slow; and I was accomplishing the steps. We achieved adequate space on the Airbus; and had LOC/GS captured; ran the checklist; and proceeded to land. When the transfer of controls was complete; and I called flaps up; the First Officer noted the flaps at 25.I had failed to move them to 30 completely and; due the fact that I had the lights very dim for the visual approach at night; we both missed the improper setting. Fortunately; we had a wind additive for conditions and no control or performance issues were noted. We debriefed the error; and are both aware of the need to be more alert and cross check configurations and settings.
B737 flight crew reported landing with flaps 25 after encountering wake turbulence on approach to TPA in trail of an A320.