UPDATED 11.54am: Those evacuated due to a 12 hectare scrub fire on Waiheke Island overnight, are back in their homes for New Year's Day.

At least 30 homes were evacuated in the Orapiu Road area.

A fire service spokesperson said the fire is now under control, but isn't completely out.

Firefighters have been battling the blaze since 1.30 this morning, hampered by hilly terrain and wind gusts.

Waiheke Island volunteer firefighters have been joined by several crews sent from Auckland, as well as two helicopters.

There have also been three house fires in Auckland overnight - and at least four scrub fires in Northland, in Monganui, Horeke, Omapere, and Ruakaka areas, all fanned by strong winds.