Niagara Falls Frozen: Ice, Records and Winter Flow Facts

Does Niagara Falls freeze solid?

Photos of a white, ice-covered Niagara Falls circulate every cold winter, but the river does not stop. New York State Parks states that the only documented case of the falls being described as frozen completely came in March 1848, and that the cause was ice damming at the mouth of Lake Erie, not a frozen waterfall. The same agency notes that even during the Polar Vortex of 2014 the falls continued to flow.

What freezes is the edge of the picture. Spray from the falls coats rocks, railings and trees on both banks, and ice builds up along the brink and in the gorge below. Behind and under that shell, water keeps moving over the crest. The International Joint Commission (IJC), the U.S.-Canada body that oversees the river, also points out that the control works upstream of the falls do not reach across the whole Niagara River, so the flow over the falls cannot be shut off completely by those structures.

The 1848 ice jam

The 1848 event is the one most often called the time Niagara froze. New York State Parks describes it as ice damming at the outlet of Lake Erie in March 1848. Ice packed into the head of the river near Buffalo and cut off most of the water feeding the falls for a short period. Because the cause was a blockage upstream, the falls ran low rather than turning to solid ice.

A separate event is often mixed up with 1848. In the summer and fall of 1969, the American Falls were dewatered on purpose so engineers could study erosion of the rock face. The IJC notes that flow over the Horseshoe Falls continued the whole time, so photos of a dry American Falls from 1969 have nothing to do with ice.

Ice bridges below the falls

In very cold winters, ice from Lake Erie and the upper river can pile up in the gorge below the falls and freeze into a solid mass called an ice bridge. New York State Parks states that in the early 1900s tourists often walked out onto these ice bridges and that the practice was forbidden after February 1914. A widely documented ice bridge broke apart with visitors on it on February 4, 1912, according to the Niagara Falls Public Library in Ontario and a Brock University archive exhibit. Walking on the river ice at the falls has not been allowed since that era.

The Lake Erie ice boom

Since 1964, a floating barrier called the Lake Erie-Niagara River Ice Boom has been placed each winter across the outlet of Lake Erie, southwest of the Buffalo water intake. The IJC describes it as 8,800 feet long, made of 22 spans of steel pontoons. It is owned and operated by the New York Power Authority (NYPA) and Ontario Power Generation (OPG).

The boom speeds up the formation of a natural ice arch at the head of the river. That arch reduces how often and how long large runs of lake ice enter the Niagara River, which lowers the risk of ice jams, shoreline damage and reduced water at the hydropower intakes. Under the IJC rules, installation can begin on December 16 or when Lake Erie water at the Buffalo intake reaches 39 degrees F (4 degrees C), whichever comes first. The boom must be removed by April 1 unless ice cover on eastern Lake Erie is still larger than 250 square miles. New York State Parks credits the boom with making a repeat of the 1848 stoppage very unlikely. A 1983 National Academy of Sciences study cited by the IJC found no evidence that the boom changes winter temperatures in the Niagara area.

How much water goes over the falls in winter

The 1950 Niagara Treaty between the United States and Canada sets minimum flows over the falls, and the rest of the river can be diverted to the power plants on both sides. The IJC lists the minimums as follows.

So the winter falls run on the lower treaty minimum of 50,000 cubic feet per second (1,416 cubic meters per second), half the daytime summer figure. The Niagara Parks Commission in Ontario gives the drop of the Horseshoe Falls as about 188 feet and the height of the American Falls as 70 to 110 feet from the crest to the rock pile at its base.

The coldest months at Niagara

Ice on the falls builds during long stretches below freezing. The nearest official NOAA climate normals are for Buffalo, about 20 miles upriver, published by the National Weather Service in Buffalo for 1991 to 2020.

January is the coldest month in the Buffalo normals, followed closely by February. Those are also the months when photos of a heavily iced Niagara Falls usually appear. Niagara Falls State Park stays open all year, and New York State Parks lists the frozen falls among the park's winter sights.