Two major fires have merged into one massive blaze on Christchurch's Port Hills.
Despite cooler temperatures overnight and higher humidity, the fire now covers more than 1,800 hectares and is still slowly advancing.
Helicopters will be up at first light, when officials expect to be able to get the most accurate picture of the size of the fire.
Christchurch Civil Defence spokesman Dave Adamson says they can't rule out losing more homes on Thursday.
"Overnight it's got cooler, the humidity's lifted so the fire's lost a little bit of its aggression. However as the morning heats up we are expecting reasonably high temperatures this afternoon and also reasonably high winds, so as the day progresses it's pretty hard to predict.
"As the day warms up those fire fronts will liven themselves up, so it just depends on how much resourcing we can get into the air, how much we can get onto those fronts."
The biggest concern for the fire service on Thursday is that the fire will spread to the suburb of Westmoreland.
Meterologist Richard Green says the easing winds and rising humidity will assist firefighters.
"It looks like the wind is going to be consistent," he says. "This is the first time we've seen this since the fire broke out earlier in the week. Northeasterly winds - they died down overnight and became almost calm, which was a pleasant change for the firefighters."
Investigators are preparing to recover the helicopter that crashed during firefighting operations above the Port Hills, killing pilot Steve Askin.
The Transport Accident Investigation Commission is hoping to recover the Squirrel chopper on Thursday morning.
Investigator-in-charge Ian McClelland and two colleagues spent much of Wednesday at the crash site, surveying the wreckage, taking notes and recovering some items.
Mr McClelland says much would depend on the weather and the fire, which reached within 1.5km of the crash site.
Mr Askin, a 38-year-old father of two, died at the scene of the crash near Sugarloaf carpark on Tuesday.
He was a former member of the SAS and received the New Zealand Gallantry Star, the country's second-highest gallantry award, in 2014 for his actions during a Taliban attack in Afghanistan three years earlier.
NZN / Newshub.