Dozens of firefighters and five helicopters are at Tongariro National Park this morning to tackle a large vegetation blaze.

Mild conditions overnight helped firefighters keep the fire to 322 hectares.

Fire and Emergency said four helicopters would be using monsoon buckets today and a fifth would coordinate the air attack.

Planes were on standby if needed, the service said.

The air fleet would help 30 firefighters on the ground.

Three crews of firefighters dealt with a flare-up overnight.

Fire and Emergency operations director Brendan Nally told Herald NOW things were “looking quite good this morning”.

“We’ve got favourable conditions today. The containment lines are well advanced, and we’ll have this mopped up and moving into just hotspot work over the next couple of days.”

He said the wind was moving around “a little bit”, but not as much as when a large vegetation fire burned thousands of hectares in Tongariro National Park last month.

Temperatures would be in the mid-20C range in parts of the area today, which would make it tough for fire crews, he said.

“There’s an outside chance of a little rain, but it won’t be significant enough to really help.

“So it’ll be our helicopters and [planes] that will do the damage today.”

State Highway 47 between SH46 and SH48 is closed because of the fire.

The New Zealand Transport Agency advised drivers to allow extra time for travel.

Southbound motorists should detour via SH1 and SH49, with the reverse applying for northbound travellers.

One of the fire flanks had come up on the burned-out area of last month’s fire, which had allowed crews to concentrate resources on the fire’s other flank, Nally said.

Fire and Emergency crews were alerted about 1.10pm yesterday to the blaze on the eastern side of State Highway 47.

Yesterday, Nally said an investigation was underway, with initial indications that the fire was not arson.