Firefighters battling a bushfire are working to protect an old trapper's hut where the last wild Tasmanian tiger was captured.

Key points: Large bushfire now 10km from historic and culturally significant sites

Large bushfire now 10km from historic and culturally significant sites Weather conditions heating up over weekend

Weather conditions heating up over weekend Blaze likely to be burning until February

A fire has ravaged the state's south-west wilderness area and is about 10 kilometres from Churchill's Hut, near Tim Shea.

The hut was built in the early 1920s by Elias Churchill, who went on to catch the last wild Tasmanian tiger in 1933 for Beaumaris Zoo in Hobart.

Parks and Wildlife Service (PWS) officer Nic Deka said Churchill's Hut is one of several culturally significant sites that may be affected by the fire, which was sparked by lightning strikes 12 days ago and has now burnt through more than 20,000 hectares.

The last Tasmanian tiger was trapped in the Florentine area and died at the Beaumaris Zoo in Hobart in 1936. ( Wikimedia Commons )

"We've got Morley's Hut down at Adamsfield, we've also got Churchill's Hut, which is over towards Tim Shea," Mr Deka said.

"We also have some Aboriginal sites of significance in that part of the world that we're monitoring to make sure there's no unacceptable impacts on those."

PWS said it was unable to comment on the nature of the Aboriginal sites potentially under threat from the fire for cultural reasons.

Members of Tasmania's Aboriginal community also declined to comment.

Interstate firefighters have helped protect sensitive areas around Lake Rhona. ( Supplied: NSW Rural Fire Service )

Ground crews are extinguishing spot fires by hand, as waterbombing takes place overhead. ( TFS: Warren Frey )

A sprinkler line has been used at Lake Rhona to protect sensitive vegetation and PWS said it would be using similar tactics to protect the identified sites of cultural significance.

"We've used irrigation systems previously — I think it's probably fair to say that we haven't used them as extensively as we are currently using them in a firefighting sense," Mr Deka said.

"They have proven very effective at Lake Rhona and we're also looking to utilise sprinkler systems to help with fall back contingencies to protect heritage structures further south of the fire just in case the worst happens and the fire starts to take another run."

The Tasmania Fire Service's Steven Richardson said firefighters were getting "traction" but described it as tough, slow and difficult work with the weather conditions set to worsen again.

"Over the next few days the weather will be on our side and, while it still will be windy, the temperatures won't be as high as they have been," he said.

"It does give us the chance to put in some effective and efficient firefighting tactics on the ground.

"But we do know that coming around by around Saturday, the weather will deteriorate again so we're just trying to consolidate what we can at this point in time ahead of the weather getting worse."

Sorry, this video has expired Aerial vision and infrared imagery shows the fire burning in Tasmania's south west (NSW Rural Fire Service)

"Long term we are working with the Bureau of Meteorology to look at what the long-term weather effects are going to be to help us predict how long we will be up here for," the TFS's Steven Richardson said.

The forecast for the central south west area over the coming days is for temperatures in the mid to high twenties, with Tuesday predicted to reach 31 degrees Celsius.

Firefighters say it is tough and slow going trying to control the flames. ( ABC News )

Firefighters admit it is a case of strengthening containment lines and waiting for rain to put it out.

"There's no rain in the next several days, there's a few minor promises but zero to five millimetres isn't all that encouraging so really it's going to take a significant rainfall event to do any real good," Mr Deka said.

"Unless we get significant rain we'll be managing the fire for sometime to come dealing with hotspots."

It is unlikely the blaze will be out before February.