Power has now been restored after about 30,000 Hydro One customers were affected by power outages through Huron, Perth, Bruce, Grey and Wellington.
That included customers of smaller utilities in many communities served by entities such as Westario.
Equipment failure is being blamed for the outages although Hydro One does not have any specifics.
The first of the outages were reported just before 8:30 a.m. on Thursday.