Narrative:

I was flying from ZZZ - ZZZ1. I was pilot monitoring and my first officer was pilot flying. The weather at the time was heavy rain; 4 sm visibility; and overcast at 2;200 ft. At the time ZZZ was in a south flow and we were set up for runway xxr. After we pushed back; ran the after start checklist and were ready to taxi; ground informed us that they were switching to a north flow and to expect runway xyr; and stated the winds were '300 at 14 kts.' I stopped; re-entered the numbers in ACARS and the new numbers for runway xyr were flaps 20 instead of flaps 8; which I promptly read out and pointed at. Somehow; however; the new flap position did not get selected. I then called for the runway change checklist; ran it; and began our taxi. Upon commencing the takeoff roll and passing through 80 knots; I was doing my scan of the instruments and noticed the flaps were still at 8 and not 20; so I selected 20. We got a 'config flaps' warning which promptly went away as soon as the flaps reached their newly commanded position so I continued the takeoff roll and lifted off without any issues.the reason I elected not to abort the takeoff was because we were in heavy rain and the aircraft only had one operable thrust reverser. Adding a 'flaps __' item in the before takeoff above the line checklist but the barriers that are currently in place have been sufficient numerous times before. I simply made a mistake that I have learned from and that will make me more vigilant and observant in my duties.

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Original NASA ASRS Text

Title: CRJ Captain reported that distraction and a runway change resulted in takeoff with an incorrect flap setting.

Narrative: I was flying from ZZZ - ZZZ1. I was Pilot Monitoring and my First Officer was Pilot Flying. The weather at the time was heavy rain; 4 sm visibility; and overcast at 2;200 ft. At the time ZZZ was in a south flow and we were set up for Runway XXR. After we pushed back; ran the after start checklist and were ready to taxi; ground informed us that they were switching to a north flow and to expect Runway XYR; and stated the winds were '300 at 14 kts.' I stopped; re-entered the numbers in ACARS and the new numbers for Runway XYR were flaps 20 instead of flaps 8; which I promptly read out and pointed at. Somehow; however; the new flap position did not get selected. I then called for the runway change checklist; ran it; and began our taxi. Upon commencing the takeoff roll and passing through 80 knots; I was doing my scan of the instruments and noticed the flaps were still at 8 and not 20; so I selected 20. We got a 'config flaps' warning which promptly went away as soon as the flaps reached their newly commanded position so I continued the takeoff roll and lifted off without any issues.The reason I elected not to abort the takeoff was because we were in heavy rain and the aircraft only had one operable thrust reverser. Adding a 'flaps __' item in the before takeoff above the line checklist but the barriers that are currently in place have been sufficient numerous times before. I simply made a mistake that I have learned from and that will make me more vigilant and observant in my duties.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.