Firefighters were waging a running battle with the Winter Hill blaze this afternoon as pockets of flame kept breaking out.
Crews are expected to remain on site through the weekend.
A Lancashire Fire and Rescue Service spokesman said: "The fire has never really gone out. Firefighters get on top of it and then the wind changes and it can go up again.
"The ground is so dry this will keep going on over the weekend and day after day until it rains - and there is none forecast."
This afternoon around 50 Greater Manchester officers were dealing with a new site - Scout Road near Horrocks Moor in Bolton.
"Please stay away from the area and as usual, keep windows and doors closed if affected by smoke," said the fire service.
Crews were initially called to multiple fires on the hills near to Horrocks Moor Farm at 2am this morning (Friday, June 29.)
Six fire engines tackled the flames throughout the night and this morning just two crews remained on the scene dampening down hot spots.
However, due to the intense heat and dry weather, the fire flared up again early this afternoon and a total of ten pumps plus a number of officers were sent to fight the fire using specialist wildfire equipment.
The fire currently measures approximately 2km in length.
People are advised to stay away from the area and nearby residents are asked to keep their windows and doors closed where possible.
Meanwhile firefighters have thanked well-wishers for all their supplies for water and snacks to keep them going through the many hours tackling the blaze.
The Lancashire Fire and Rescue Service training centre at Euxton is the collection point..
They tweeted: " Huge thanks to all the kind messages we’ve had from the people of Lancashire & beyond offering donations for our hardworking crews".
Deputy Chief Fire Officer Justin Johnston said officers were battling to get under the peat to kill off the blaze..
There was a possibility that water be brought in later today by helicopter.
A Chorley Council spokesman said: "We know that Rivington is a popular visitor destination - while the fires are being tackled people are being advised not to go up there.
"People going up and taking a look have hampered the operation and created unnecessary risks."