The cause of the fire has not yet been determined, but Boag said the blaze was "a bit strange" because the ground should have been damp after last weekend's deluge.
Nearby resident Jenna Harvey said she was first told by a neighbour about the blaze on the farm behind her house.
"You could smell it... Smoke was filling the street."
She said her main concern was the fire's movement, and she was "hoping it did not jump the hill and spread".
By 2.40pm the fire was under control and crews were dampening down hotpots.
Ngongotaha residents are still recovering from extensive flooding damage from torrential rain last Sunday.
A state of emergency is still in place after the flooding.