During the 18 or more days they are expected to be in Tasmania, the two New Zealand crews of six - one group made up of Department of Conservation staff from Northland, and another of forestry workers from Nelson, aged 31-60, plus a liaison officer - will be working in remote areas.
They will possibly be camping in the bush while battling to contain the fires that have so far destroyed more than 100 properties.
It will be "hot, tiring" work, said group liaison officer National Rural Fire Authority rural fire manager John Barnes of Christchurch, who has been on four previous deployments to Australia and the US.
"They're going to have to keep their fluids up. It's very tough work."
Two of the firefighters and Mr Barnes have previously been deployed overseas and were looking forward to helping in Australia in spite of the risks.
"It's just a part of the job. I'm feeling a little bit nervous but once you get there it's just game face on," said the youngest firefighter, 31-year-old Matiu Mataira, a father of two from Whangarei.
When they arrive the team will spend the first day becoming familiar with the equipment and terrain.
Temperatures in New South Wales have reached the mid 40s - among the highest temperatures on record for the state.
Bushfires are also burning in the Australian Capital Territory, Victoria and New South Wales. South Australia is also bracing for the worst bushfire conditions in years.
Over the past decade New Zealand firefighters have been deployed several times to assist Australians fighting bushfires. The largest group was sent was in 2009 when 110 rural firefighters were deployed to Victoria.
Temperatures cool
Meanwhile, Australia is getting some relief, with temperatures cooling from record highs across much of southern Australia today, reducing the danger from scores of wildfires that have blazed for days.
Australia recorded its hottest day on record on Monday with a nationwide average of 40.33 degrees Celsius, narrowly breaking a 1972 record of 40.17C.
The Bureau of Meteorology will calculate later Wednesday whether Tuesday's average was even hotter. With Wednesday's cool-down, the national capital, Canberra, dropped from a high of 36C on Tuesday to 28C and Sydney dropped from 43C to 23C.
No deaths have been reported, although around 100 people haven't been unaccounted for since last week when a fire destroyed around 90 homes in the Tasmanian town of Dunalley, east of the state capital of Hobart. On Wednesday, police spokeswoman Lisa Stingel said it's likely most of those people simply haven't checked in with officials.
"There are no reports of missing persons in circumstances that cause us to have grave fears for their safety at this time,'' Tasmania Police Acting Commissioner Scott Tilyard said in a statement.
Thousands of cattle and sheep as well as wildlife are suspected to have been killed.
In Victoria state, north of Tasmania, a fire injured six people, destroyed four homes and caused the evacuation of the farming community of Carngham, Country Fire Authority operations officer Ian Morley said.
Cooler conditions on Wednesday had brought relief to firefighters who would work through the day to build earth breaks to fully contain the fire ahead of warmer temperatures forecast for Friday, Morley said.
"We have had very mild, cool conditions overnight which is a great help to the fire suppression effort,'' he said.
North of Victoria in New South Wales, Australia's most populous state, firefighters were battling 141 fires, including 31 that had not yet been contained.
Fires have burnt through more than 131,000 hectares (324,000 acres) of forest and farmland since Tuesday, but the Rural Fire Service has reported only one home destroyed there.
A fire was burning out of control in the Kybeyan Valley east of the town of Cooma.
Police knocked on doors to advise residents of the danger, with the blaze predicted to move toward the villages of Dangelong, Numeralla and Countegany.
Rural Fire Service Deputy Commissioner Rob Rogers said the cool reprieve was expected to be short-lived, with temperatures forecast to climb again by the end of the week.
"We don't need new fires today,'' he said.
The fires have been most devastating in Tasmania where at least 128 homes have been destroyed since Friday.
Hundreds of people remain at two evacuation centers in the state's south, as fires continue to burn more than 80,000 hectares since last week.
"People have lost everything. We can't comprehend that devastation unless we are in their shoes,'' Tasmanian Premier Lara Giddings said.
The fires have consumed over 80,000 hectares (198,000 acres) in Tasmania since last week.
Wildfires are common during the Australian summer. Fires in February 2009 killed 173 people and destroyed more than 2,000 homes in Victoria state.
- APNZ / AP
