Photos and videos posted online by nearby locals showed a large plume of smoke rising into the air.
A strong 16kmp/h north-easterly wind helped fuel the flames and encourage the blaze to spread.
Whangārei Heads fire chief Paul MacDonald said it was started by a car's exhaust pipe as the vehicle was driven through long Kikuyu grass on the property.
"Just because it's winter doesn't mean there aren't still any fire risks," he said.
MacDonald said there were no concerns about the blaze potentially threatening a house on the property.
Firefighters were still on site dampening hot spots alongside the helicopter at 6pm.
Northland's fire brigades remain fully operational during Alert Level 4. However, firefighters will don PPE and will stick solely to their crews as part of strict social distancing rules.
Fire and Emergency New Zealand (FENZ) assistant area commander for Whangārei/Kaipara, Graeme Quensell, urged people to take extra care around their homes to, both, keep themselves safe and to avoid exposing emergency workers to any risks while on the frontline.
"Lockdown means there's an increase of people at home. Quite often families will return home to spend lockdown together, especially in the Far North, so there are houses full of people."
"That means more phones are on chargers, fires are going, heaters are on. Make sure your smoke alarms are working and you know what to do if they go off. Just be extra careful," Quensell said.