The woman, a Swiss citizen who moved to Kerikeri in 2000 with her late husband, was unhurt, as was her dog.
Fire safety officer Gary Beer said it wasn't clear what had woken the woman up.
''But thank God she did,'' he said.
The fire was not suspicious and nothing had been left switched on in the kitchen or left in the drier.
Beer suspected the cause was an electrical fault in the roof cavity so he was focusing his investigation on that area. Firefighters had managed to retrieve some personal belongings yesterday morning.
Neighbours also arrived to help recover items which had survived, including framed photos of her children which were cracked and smoke-damaged but still intact.
The 88-year-old, whose children live in Switzerland, and her dog are staying with neighbours Barry Slabosz and Roslyn Wakefield.
Neighbours had already brought her clothing and had informed Age Concern to see what could be done to help her. The woman had home and contents insurance.
The property is surrounded by trees but the flames did not spread beyond the house despite the dry conditions. Beer said it had helped that the trees were set back from the house and shrubs planted nearby were low-flammable types.