Fire and Emergency was alerted around 1pm to the fast-moving fire near Cheviot.
Crews from Cheviot, Hurunui, Waipara, Scargill and Motunau are at the scene, plus a command unit from Christchurch and heavy machinery diggers.
A spokesperson said the flames had jumped the Hurunui River but it was hoped that a large hill would slow down the fire.It had already burned through around 100 hectares of vegetation.
Firefighters spent last weekend extinguishing fires at Amberley, Loburn and on the Waimakariri Riverbank, northwest of Christchurch.
Meanwhile, NZTA Waka Kotahi has warned drivers to take care on State Highway 73 between Kumara and Arthur's Pass due to strong winds.
"Please take extra care, especially if you are in a lighter or high-sided vehicle or riding a motorcycle."