Power has been restored to north Queensland after a massive outage blacked out all homes and businesses north of Townsville.

Powerlink Queensland chief operating officer Simon Bartlett said crews worked as quickly as possible to restore power to the Cairns and Townsville regions at about 7.40pm (AEST) on Thursday.

He said the outage was caused by simultaneous faults on two of the high voltage transmission lines that supply electricity to north Queensland at about 5.30pm (AEST).

"We appreciate the community's patience and understanding during the restoration efforts," Mr Bartlett said in a statement.

"Crews will be working overnight to inspect the powerlines which were affected by the unexpected electrical fault and repair any damage to the network."

A lightning strike could be to blame, but it was too early to determine the cause, he said.

"We've had some really severe lightning storms, as everyone knows, throughout the state, and these lightning bolts can hit the transmission system," he told the ABC.