Nicole Wignall, 16, had helped build the huge ball of ice – the size of a small car - with friends before it rolled down a hill and smashed her into a wall, breaking her pelvis in four places.
She was rushed to hospital where doctors said the impact of the 4ft x 4ft snowball was the equivalent of crashing a motorbike at speed.
College student Nicole, who built the snowball after getting the day off lessons because of bad weather, said: "It took seven of us to push it. We got it to the top of a steep hill, then we had a break.
"I was chatting with my friend and suddenly we saw the snowball coming down really fast.
"My friend moved out of the way but I froze on the spot and the snowball smashed into me.
"I ended up squashed against the wall with this massive weight on me. I think I went into shock. "I was screaming in pain. It was really bad and I couldn't move my legs.
"Nobody could move the snowball. My friend pulled me out and I was on the floor until paramedics came. It all happened so fast."
Nicole will be in a wheelchair for weeks after last Monday's accident. She may need months of physio before she can walk again.
Mum Fiona, 38, said: "It was the size of a small car. She had a very lucky escape."