Residents of Canterbury's Castle Hill village have been encouraged to evacuate as a spreading scrub fire at Bridge Hill continues to burn out of control.
Incident Commander Brian Keown says it is possible, but not probable, the blaze will reach the village overnight.
While not an evacuation order, Keown said it would be easier to leave now than in the middle of the night.
Fire and Emergency New Zealand (Fenz) were first alerted to the blaze at 4.24am and what began as a 2ha fire had by this evening grown to about 535ha.
Nine helicopters, three planes, and 12 trucks, tankers and support vehicles are among the resources being thrown at the blaze.
Three school camps staying about a kilometre from the fireground have been evacuated as a precaution, as has Flock Hill Lodge.
State Highway 73 is closed between Castle Hill and Arthur's Pass village.
Containment efforts had been hampered by high winds and extreme fire behaviour, Fenz said.
MetService meteorologist Sarah Haddon earlier said gales were hitting higher altitudes but lower elevations also had strong winds, RNZ reported. Winds were expected to start to ease slightly from Thursday afternoon and not expected to die out until later on Friday.
This evening he encouraged people to consider leaving their properties.
"It is a lot easier for people to leave now rather than trying to complete an emergency evacuation in the middle of the night, so we are encouraging people to stay with friends and family or return home if this is their holiday home.
"In the unlikely event that the fire does reach the village, an evacuation order will be made via Emergency Mobile Alert and door knocking, and we will then do everything in our power to protect the properties if it is safe to do so.
"This is not an evacuation order so if people want to stay they can, but they must be prepared to evacuate at very short notice."
Selwyn District Council and Fire and Emergency personnel were going door-to-door to advise residents of the self-evacuation advice.
Keown said people should be prepared to leave their homes and take what they need.
"This includes important documents, medication, supplies for pets and other animals, and personal items needed for a couple of days.
Two were staying at the Environmental Education Centre and the other at Forest Lodge.
In the 4.25pm update Keown said Flock Hill Lodge, which had been used as an evacuation point for one of the schools previously evacuated, had in turn been evacuated as a precaution.
No other evacuations had taken place.
"Outside of the three schools evacuated from the Environmental Education Centre and Forest Lodge, all other school camps are safe and away from the fire.
"Parents can be assured that their children are not in danger."
SH73 was closed between Castle Hill and Arthur's Pass about 9.30am.
The road would remain shut for some time, he advised.
People should avoid the area and look to make alterative travel arrangements if they were planning to use this road today."
NZ Transport Agency/Waka Kotahi said road users should consider using SH7 as an alternative route.
Police said diversions are in place on SH73 at Castle Hill Village, Arthur's Pass, and Springfield near Annavale Rd.
