Fire crews feared a scrub fire in the Castlecliff sand dunes would spread to nearby houses if the strong wind changed direction.
David Utumapu, Fire and Emergency New Zealand's assistant area commander for Whanganui, said at the height of the incident on Monday evening, there were three urban and three rural fire trucks on the scene near the Seafront Rd and Bamber St corner.
The dunes back on to Carson St and Ashton Tce, raising concerns about houses in that area.
"Initially there was some concern that if the wind blew in the wrong direction the fire would have blown towards houses," Mr Utumapu said.
"It was a large area of burning tussock about 200m long and 80m wide.
"The wind was quite strong and changed direction. It's very difficult to find the cause of fires of this nature, given the burnt area and because the wind moved around a bit.
"It wasn't easy for us to track back to where the fire started so at this stage the cause is undetermined.
"The crews did a good job to contain the fire to that particular area."
Mr Utumapu said it was fortunate that the volunteer rural fire team was at the fire station for training when the call came in so they were able to respond immediately.
"Fires of this nature are quite people-hungry and equipment-hungry," Mr Utumapu said.
"The crews left the scene at 9.30pm so that was about three hours for the call but it was after 11pm by the time they finished the clean-up back at the station."
Castlecliff resident Lynne Douglas saw smoke as she was heading out and first thought it was coming from the Longbeach area.
"Then I turned the corner to Bamber St and there it was," Mrs Douglas said.
"I went round to Carson St and got up on the hill there. There were quite a few people standing up on the hill watching.
"It was fortunate we had a southerly wind taking the fire toward the Bamber St area whereas had it turned and come back towards the houses in Ashton Tce it wouldn't have been good."
Mrs Douglas said the coastal area was "tinder dry".
Monday's fire follows a larger fire in Castlecliff on Thursday, December 14. A helicopter was needed to fight that 2.5 hectare fire along a section of coastline between Castlecliff Beach and Kai Iwi Beach, 4km west of Seafront Rd.
"It's good for people to be really aware of what's happening around them, especially in coastal areas where it's really dry," Mr Utumapu said.