Witnesses say the blaze has broken out in a forest area on the city's green belt, about 100 metres from neighbouring homes.
Local resident Paula is in Wadestown and said "it's tinder dry. We can see the flames. It's quite big.
"The wind is blowing it away towards the trees, away from the houses, but there's lots of trees there."
Newstalk ZB's Katrina Bennett is near the fire scene.Bennett said police are manning a cordon around the blaze.
"You can see flames in the trees, still shooting up into the sky.
"There's a lot of smoke, and a bit of a haze in the sky as well."