Firefighters are working 24/7 to fully extinguish the large vegetation fire at Brandon Hall Rd/Pukepapa Rd Ext at Santoft, west of Bulls.
The fire, which started on Saturday, reached around 78ha in size and it is expected to be "quite some time" before fire crews wind up at the scene.
Vegetation fires aren't declared out until every possible source of re-ignition is extinguished, including fire that may be smouldering underground.
Crews from Whanganui, Marton, Hunterville, Koitiata, Bulls, Rangitīkei, Ohakea, Palmerston North, Hāwera, Halcombe, Rongotea, Feilding, Wellington and Upper Hutt have been involved in fighting the fire.
Rangitīkei Rural Fire staff say firefighters have been using "every tool in the box" including hand tools, pumps, appliances, tankers, diggers, tractors, bulldozers, hand-held thermal imaging, aerial thermal imaging, helicopters and drones.