Up to 30 homes wrecked in Sydney storm

Up to 30 Sydney homes are uninhabitable following the thunderstorms that lashed southern Sydney on Wednesday morning.

Record gusts in excess of 200km/h hit the suburb of Kurnell, causing major damage to schools, houses and plants.

The NSW State Emergency Service Deputy Commissioner Greg Newton said many areas of Sydney remained a mess.

"Some properties, 25 to 30, have been quite extensively damaged," Mr Newton told the Seven Network.

"Roofs pulled off and other structural damage.

"That will make those properties uninhabitable."

He said four-to-five hour delays remain at Sydney Airport.