Crew members are still at the scene and will remain there for much of the day.
West Yorkshire Fire Service say the blaze on Marsden Moor looks to be out.
Crews have been at the scene at the scene between Manchester and Huddersfield since it started at around 7.30pm last night (27/2).
More than 30 firefighters from West Yorkshire and Greater Manchester fire stations were deployed and police were forced to close the A62 between the Colne Valley and Diggle in both directions to protect the public.
Dramatic photographs have been shared on social media of the fire, which turned the night sky orange.
Thank you to Nick Lawton and Victoria Alfrey who sent us these photos of the blaze overnight and this morning:
The blaze erupted on National Trust property near Marsden and covered about one-and-a-half square kilometres of land at its peak, with firefighters having worked through the night to try to extinguish it.
One witness described the blaze as an "apocalyptic scene", which some have said is reminiscent of the "unprecedented" blaze that spread across the moor last summer.
The army was scrambled to help police and firefighters cope with those flames, which took three weeks to be completely extinguished amid a scorching heatwave.
NEWS: Firefighters are still tackling a large blaze at West Yorkshire's #SaddleworthMoor.— Pulse 2 (@Pulse2Radio) February 27, 2019
An area of around 1-point-5 square kilometres has been burning near Marsden.
Huge thank you to Nick Lawton who kindly shared these dramatic photos with #Pulse2
Station Manager Adam Greenwood attended the fire overnight.
He said: “When crews arrived shortly before 20.00 hrs there was a large area of approximately three to four square kilometres of moorland on fire. It was one of the of the highest flame fronts we have seen with flames of up to two metres high and it was moving fast across the moorland.
“The top layer of the moorland is quite dried out because of the recent good weather and underneath is quite damp so it has run across the surface of dry vegetation.
“Two specialist wildfire units were there and approximately 30 firefighters tackling the fire. It was really adverse conditions. We were rotating the crews for their welfare as it’s very physically demanding work.
“Crews were walking up to a mile to reach the fire and were carrying blowers, beaters and other firefighting equipment with them. Crews have worked tirelessly to get fire under control and have done a great job. The quick initial fire attack by firefighters did help to bring the fire under control, despite the size and ferocity of the flames.”
One witness, John Turner, told us: "There were lines of flames, like someone had put down petrol on the hillside and it was just a massive ring that went zigzagging up and down the hill and all around in a circle.
"It's like the sky is on fire, almost.
"There was a group on the hill, just pulled over, and there were people saying 'it looks like the end of the world, it looks like the apocalypse is happening'."
The dramatic scenes, which could be seen from miles away, come just a week after fire crews had to put out another blaze on the moor.
No injuries have been reported at Marsden.