The pair traversed across to the 19-year-old, who was hiking around the lower reaches of the mountain in shorts and sandshoes and was on his own.
They could see him sliding down a slope on his backside using his hands to push himself forward.
"He was totally unprepared. Initially we got him stabilised, we could see had been using his hands to get himself down the mountain and he was bloody cold because he had wet nylon shorts on."
"He was in trauma and in shock. It's easy to criticise but ....straight away we lifted him up and got some goretex underneath him and wrapped him in polar fleeces to take the chill out of him. We put a hat on his head and we stabilised him," he said.
Mr Lowry said Wanja was "incredibly lucky" as there was no-one else on the hill.
"He would have perished because the skies opened up on Sunday night and it was rather cold - I would suspect it would have got below zero probably minus 5 where he was in the snow."
"He was a pretty lucky young man but a foolish young man as well."