Bushwalk Australia

Niagara Falls region freezes as storm system sweeps through North America

ABC

https://mobile.abc.net.au/news/2019-01- ... w/10743992

"A cold weather system strengthened by Arctic air has helped freeze the area around the falls
More cold weather is expected to prolong the stunning scenes, with freezing rain on the way
Niagara Falls have only completely frozen over once before, back in 1848"

Must have been cold back then because in 1848 the flow rate over the falls was much higher, today most of the flow is diverted for hydro power, which incidentally has reduced the erosion of the face of the falls substantially.
Colloquially that year was known as Eighteen hundred and froze to death