Up until about the mid 1960’s, people (non-Jews and Jews alike) would “dress up” when going in public. This included going out to shop; or when attending classes in college; or even to a ball game: men would go out in public in their fedoras, dress slacks, jacket and tie; similar for women.
This did not change in hot weather; only the type and thickness of the cloth: Hats were of straw instead of felt; short sleeve shirts; suits were of the lighter seersucker type.