Warwicks batted first and were doing reasonable well until Neil Carter lost his wicket. This started the usual Warwickshire collapse and with 25 balls to go, they were on 97-7.
Keith Barker came in and made 39 which along with 27 from Chris Woakes saw Warwicks who had Jon Trott back close on 145-8.
Adam Lyth made 31 for the visitors before he hit his wicket to become the third Yorkshire player out. Ant Botha and Imran Tahir both chipped in with two wickets apiece before Keith Barker came back to bowl.
Still needing fourteen to win with four balls, Keith Barker had Pyrah caught by Clarke and with his next ball had McKay caught by Clarke. The hat-trick was on and Barker bowled Wainwright first ball to give Warwickshire a 14 run victory.
Warwickshire are at home to Worcestershire on Friday. Play is due to start at 5.30pm.