Costco is open from 10:00 AM to 8:30 PM Monday through Friday, 9:30 AM to 6:00 PM on Saturday, and 10:00 AM to 5:00 PM on Sunday. Costco is closed on most major holidays.
In Canada, Costco stores are closed on Canada Day, Labor Day, Christmas Day, and New Years' Day without exception. Stores are open on Christmas Eve and New Year's Eve in all provinces, however hours of operation are shortened to 10:00 AM to 5:00 PM and 9:00 AM to 5:00 PM respectively.
Costco stores are open on Boxing Day in all provinces except New Brunswick, Prince Edward Island, and Nova Scotia. Additional statutory holidays vary by province.