Monday May 19th, 2014 is Victoria Day in Canada.
As such here are what most of the Toronto area transit services are offering:
GO Transit is offering Saturday service levels.
Sunday/Holiday service levels:
Burlington Transit Handi-van (7 a.m. to 9 p.m.)
DARTS, Hamilton (6:30 a.m. to 12:30 a.m.)
Durham Regional Service, except in Brock, Scugog and Uxbridge.
Grand River Transit, plus accessibly services
Guelph Transit, plus mobility services
Hamilton Street Railway
MiWay (Mississauga Transit)
Niagara Falls Transit
St. Catharines Transit Commission
Toronto Transit Commission
York Region Transit
Other Organizations are offering no service at all, including:
Grimsby Accessible Transportation Program
Niagara-on-the-Lake Transit, plus specialized transit service
Niagara Region Transit, plus specialized transit service
Peterborough Transit, plus Handi-Van
It is highly recommended that you contact your local transit service before using their services on Monday. My list may not include every option listed above, and each agency operates on their on schedules.