Harmer attended Governor John R. Rogers High School in Puyallup, Washington, and was the President of his senior class. He played water polo and swam on the swim team. In the short documentary "Open Windows", Harmer said he only wears black, blue and brown for concerts, cutting long sleeve shirts down to three-quarter length.
In December 2009, Harmer announced via Twitter that he had become engaged.
In March 2015, Harmer's wife announced via Instagram that they are expecting a child.