Yep, 100m is a 30 story building more or less. I know these waves are big, but this would be the equivalent of a wave height of Big Ben or the full Statue of Liberty.
I thought about visiting Nazare to watch the waves. How likely are you to see 20m+ waves on a random day in winter? How good is the view from the shore?
10m in Winter is normal. It's huge, it's dangerous and it's directly at the lighthouse. Excellent view. You also got the Supertubolos for very good surfers at the left.