Why the Saddleworth fire is likely to burn for weeks

irefighters tackle a wildfire on Winter Hill near Rivington Credit: PA

The wildfires raging across the Pennine moors has been described as 'biggest fire in living memory' and could take weeks to put out, according to the fire service.

These types of fires are a pretty rare occurrence in the UK, but with flames spreading under dry, windy conditions and another moorland blaze – on Winter Hill, near Rivington, Lancashire – breaking out on Thursday, it's getting difficult to control.

So why is this blaze so difficult to put out?

The wind

Assistant chief fire officer of Greater Manchester Fire and Rescue Service (GMFRS), Tony Hunter, cautioned that while the fire was now “contained and under control”, he said “things can develop” and if the wind blows the flames back on to the moors, it will act as a “fuel source” for the fire.

As the pressure increases at lower altitudes, the air gets warmer, the wind speed increases, and the humidity level drops.

That produces ideal conditions for a fast-moving wildfire.

The Heatwave

The operation could last for weeks before the fire burns Credit: PA

The heat dries out vegetation, making it all the more combustible if a spark ignites in the wrong place.

Mr Hunter said a good downpour of rain was needed to saturate the dry ground and vegetation – but none is forecast for days as the heatwave continues.

He said the operation could last for weeks before the fire burns itself out, though the Army deployment is for an initial 48 hours.

Peat bogs

What firefighters really need is rain and a lot of it. Credit: PA

As well as the firefighters on the ground, a helicopter has been dropping water on to the fires, but tackling a fire stretching seven square miles is an insurmountable task.

The hills on the moors are largely made up of peat bogs.

And peat burns underground, meaning dumping thousands of litres of water or retardant on top of it simply doesn’t work.

Beyond evacuation plans and firefighting tactics, what Saddleworth really needs is some help from above.

A sustained, end-of-season rainfall would soak the vegetation and lower the air temperature. But it's a waiting game.

Mr Hunter said: "It is dependent on a downpour of rain - and it would have to be a significant downpour of rain because it is so dry it would be absorbed very, very quickly."