Fenwick Colliery, which is undergoing a £7m reworking, was a wasteland of spoil heaps scorched by underground combustion, said North Tyneside Council.
"We found uncontrolled combustion of colliery waste causing temperatures of up to 1,000 degsC, making it impossible for snow to settle," said a representative.
"The heap is believed to have been burning since 1968 and our engineers had to excavate more than 120,000cu m of burning waste in order to make it safe."
Extensive landscape work included a new network of footpaths and hedgerow planting. Two shafts were also capped. A contoured landscape was designed by landscape architects from SLR, while W Marley was the subcontractor.
Main contractor Carillion Civil Engineering and consultant Parsons Brinckerhoff spend 15 months stabilising huge lagoons of slurry with 89,000m of cement columns.
Much of the 35ha site is open to the public, with the former spoil heaps fenced off to give grass time to establish. "With the programme almost complete, the project's partners came together to witness the first blanket of snow on the newly landscaped country park," the council representative added.
The Homes & Communities Agency is also contributing to work on the land at Fenwick, Eccles and West Holywell collieries, which ground to a halt in the 1980s.
"The reappearance of snow shows just how thoroughly this land has been transformed," said agency manager Martin Boys.
North Tyneside mayor Linda Arkley said: "For years, this whole area was out of bounds to the public due to contamination and now we have a safe, green area."