The professional organization I belong to (American Roentgen Ray Society) has it's annual meeting in May. The meeting was in Vancouver about 12 years ago, and it rained every day. About three years later, the meeting was in Toronto, and it was cold and wet the whole week. It even snowed one day.
They haven't been back to Canada since, but, have held the meeting in Hawaii (twice), as well as San Diego and Orlando. They're going back to San Diego next year.........