Mehaffey moved swiftly up the WAGR table in 2016 with wins in the Irish Women's Open and Welsh Ladies Open Stroke Play Championships. She was runner-up in the Scottish Ladies Open Championship, the Helen Holm. She helped Great Britain & Ireland win the Curtis Cup, compiling three and a half points out of five. She placed third in the European Ladies' Amateur Championship. She then represented Ireland in the World Amateur Team Championship, helping her country place third by finishing 15th best individual. In September she began her college career at Arizona State University.