by 
Victoria Day is a federal Canadian public holiday celebrated on the last Monday preceding May 25, in honour of Queen Victoria‘s birthday. As such, it is the Monday between the 18th to the 24th inclusive, and thus is always the penultimate Monday of May.
Across the country, Victoria Day serves as the unofficial marker of the end of the winter social season, and thus the beginning of the summer social calendar.
Victoria Day is also a mark of the beginning of the cottage season, when cottage owners may reverse the winterization of their property
