The energy giant says the shortage is mainly affecting its Petro-Pass commercial customers — mostly truckers and farmers.
A Suncor (TSX:SU) spokeswoman says the shortage began Monday and there is no immediate word on how long it might last.
Calgary-based Suncor did not release the cause of the shortage.
Suncor calls itself one of the region's largest diesel fuel producers.
People in Western Canada suffered through a diesel shortage last November and in November 2011.