Firefighters battling the Port Hills fire are making the most of calm weather conditions this morning as strong winds are expected to pick up this afternoon.

Overnight drone flights across the Port Hills fireground have identified hotspots that ground crews will be targeting in today’s firefighting operations.

There are 86 firefighters and other personnel working on the fire today, supported by diggers and bulldozers. Five helicopters are also available.

Operations manager Rob Hands surveys the damage done during the Christchurch's Port Hills fire as firefighters continue their efforts to dampen down remaining hot spots and create a buffer zone around the 24km perimeter of the fire in the Port Hills, Christchurch.

Meteorologist Mmaphapelo Makgabutlane said winds of about 5 to 10 km/h are expected to pick up later this morning around the region, which would likely be stronger in the Port Hills, potentially reaching 15 to 20km/h.

The foggy start to the day in the Christchurch region was expected to give way to sunny skies and clear conditions for today.

As the day progresses, wind speeds in the region could reach up to 40km/h, with potentially stronger winds in the Port Hills, Makgabutlane said.

A Thank You Firefighters sign is seen on Dyers Pass Rd. A large fire has broken out in Chritchurch’s Port Hills, causing mass evacuations. Photo / Joe Allison

A frontal system is expected to approach the South Island later tonight, with winds expected to start picking up.

“The inland part of Canterbury is currently under a watch for strong winds, and that starts tomorrow 5am to about 1pm in the afternoon. That is for the possibility of severe gale winds, but that’s the inland part,” she said.

• Residents evacuated due to Port Hills fire return as battle against blaze continues
• Behind the Port Hills lines: Inside the cordon as crews battle ‘grunty’ blaze
• The flames were coming: Woman loses container home in Port Hills fire
• How did the Port Hills fire start?
• Explained: The bigger picture behind the Port Hills fire

Fire and Emergency’s specialist drone crew began their work after sunset last night, and early this morning a helicopter also carrying thermal imaging equipment flew the full 24km perimeter of the fireground.

Helicopters prepare to take on day four. Photo / Joe Allison

The thermal images pinpoint areas of extreme heat that could reignite, including many that are not easily spotted from the ground.

Incident Controller Steve Kennedy says crews are making the most of favourable conditions this morning, as winds are forecast to increase this afternoon and continue tomorrow.

The investigation into the cause of the fire is continuing.

Ben Tomsett is a Multimedia Journalist for the New Zealand Herald, based in Dunedin.