Just over a century ago, in the fashion centers of America’s east coast, men were programmed to wear straw hats throughout the summer. Men who considered themselves of sufficiently high class customarily donned the requisite straw hat on May 15 (“Straw Hat Day”). This social custom was taken quite seriously by the men of that era, especially in New York City.
But after September 15, wearing a straw hat was considered a serious violation of standing etiquette.