About 25,000 households are still without power across Sydney and the Blue Mountains, after an intense burst of wild weather caused large blackouts yesterday.

Ausgrid spokesman Jonathon Hall said the damage from yesterday’s storm resulted in the largest power outage the network had seen in recent years.

“Some of the damage we have seen to the electricity network is severe and that’s even to our high voltage network as well,” he said.

The main impacted areas are in Sydney’s north, including the Lower North Shore and Upper North Shore.

Ausgrid said some customers in these areas should prepare for another night without power.

On Tuesday night, fallen trees toppled onto cars and homes in the suburbs of Gordon and Kilara, causing significant damage.

Ausgrid said it had to clear more than 1,800 dangerous hazards including fallen power lines before repairs could begin.

“Customers should prepare for another possible night without electricity while we rebuild damaged sections of the grid,” Ausgrid said.

Mr Hall said that traffic lights would also be affected in some areas.

Yesterday a wind of about 90 kilometres per hour swept through Sydney.

It was so intense that some residents called the storm that hit Gordon and Kilara worst on the Upper North Shore a “mini tornado.

The power company said it was recruiting additional crews from Newcastle and the Central Coast to restore power.

“All planned non-storm related jobs on the network have been cancelled to allow crews to focus on storm repairs,” Hall said.

Students from some schools in Sydney’s north were told to stay home today after the wild storm damaged buildings and cut their power.

The NSW Department of Education said Karonga Public School and Lindfield East Public School were closed today.

Parents at Davidson High School and Mimosa Public School were informed that they could keep their children at home due to the clean-up work on school property.

The NSW State Emergency Services (SES) said it was still working through a large backlog of calls for help.

SES spokesman Andrew Richards said hundreds of its personnel were out cleaning streets along in the Northern Beaches and Upper North Shore.

“Our crews will be coming out and removing a lot of those trees from access, such as driveways and roads,” he said.