He was a Liberal member of the Legislative Assembly of Ontario from 1955 to 1963 who represented the riding of Waterloo North.
He attended University of Notre Dame in South Bend, Indiana and graduated with a degree in Commerce and Philosophy in 1939.
In the 1959 election, the Liberals under Wintermeyer's leadership increased their legislative caucus from 10 to 21, but were unable to prevent the ruling Ontario Progressive Conservative Party of Premier Leslie Frost from winning another majority.
[4] In the campaign, Wintermeyer promoted policies such as universal medicare, improvements to general welfare assistance, amalgamation of the various municipalities that made up Metropolitan Toronto, and full funding of Catholic schools.
[2] He also served as chair of the Metro Toronto Roman Catholic high schools and the Canadian Olympic Association.