Canada’s weird winter weather phenomena

Frost flowers on lake

Forget about lacrosse (or hockey, for that matter)—discussing the weather is Canada’s real national sport. Whether it’s freezing cold or boiling hot, raining, snowing, fogging, or all three at once, meteorology is our way of breaking the ice, so to speak. And that’s when the weather’s acting…well, as normal as it gets. Sometimes, though, things get really weird—and then we’ve really got something to talk about.

These weird weather occurrences take the conversation beyond simple small talk.

Ice balls

Photo by Ekaterina Chernykh

At certain times of the year, the shores of Lake Huron and Lake Michigan look like someone’s setting up for an epic snowball fight: the beach is covered with round balls of ice, about the size of a basketball. No, it’s not someone with a snowman obsession—the balls or “boulders” are formed when chunks of ice are tossed around in the waves. If the temperatures are just right, the face of the ball that hits the wind will freeze, adding a layer of ice. If this happens often enough, large ice balls form, and eventually wash up on the shore.


Those of us who don’t live in Alberta tend to think of the province as a land of deep-freezing winter, at least from October to May. But actually, southern Albertans get regular reprieves from winter’s grip, thanks to the warm chinook winds that blow over the Rockies. What causes parts of the province to get four seasons in one day? Wet winds blow in from the Pacific coast, lose their moisture as they climb the Rockies, then warm as they blow down the other side of the mountain. Chinooks happen most often in a stretch from Pincher Creek and Crowsnest Pass to Lethbridge—although Calgary’s also famous for its warm winter winds. How dramatic are chinooks? Well, Pincher Creek had a record temperature rise of 41 degrees in one day: from -19 to 22 in an hour.

Snow rollers

Photo by Salvi 5/Wikimedia Commons

Why go to all the effort to roll piles of snow for a snowman when you can get nature to do it for you? If you live in Manitoba, that might just be possible. “Snow rollers” occur when a chunk of snow gets rolled along the ground by the wind. As it picks up more snow, the roller looks like someone started to roll snow for a snowman, then simply got up and left—or a roll of toilet paper, depending on how poetic you feel. Many times, a snow roller is actually hollow through the middle. Snow rollers don’t happen very often, but tend to be more common in hilly areas.

Frost quakes

Have you ever been snug in bed at the cottage in the winter, only to be jolted out of bed by a mysterious boom? Chances are, you’ve just experienced a cryoseism—colloquially known as a frost or ice quake. Frost quakes happen when topsoil is saturated with water that rapidly freezes, causing rocks to crack as it expands and creating those eerie nighttime booms. According to meteorologists, 2014 was a record year for frost quakes, especially in urban areas in Ontario, Quebec, and, possibly, Calgary.

Frost flowers

If you go walking in the woods on Vancouver Island at dawn in late fall, you may come across delicate ice sculptures that look like they’ve grown out of the earth. These are frost flowers—formed when the air temperature is below freezing, but the ground is still warm enough for root systems to stay alive. Plants draw water from their roots into their stems—but if the conditions are right, the water then freezes and, as it expands, pushes through the stem. Depending on the plant, the result is curling ribbons, fragile crystals or shell shapes. If you want to see frost flowers, you’ll need to get up early—they melt as soon as the sun hits them.

Thunder snow

Thunder snow is pretty much exactly what it sounds like—a thunderstorm where snow falls instead of rain. Thunder snow is rare in most areas, but is more common around the Great Lakes, where cold air passes over warmer masses of water. This not only causes the familiar lake-effect snow, but can also cause thunder. Interestingly, the snow acts as a muffler for the thunder—so while you can usually hear thunder many kilometres away from a storm, lake-effect thunder isn’t always audible unless you’re right under the storm.

Ice shoves

Photo by Cliff Harris

Ice shoves are common around the Great Lakes, and happen when strong winds push a large amount of free-floating ice onshore. The first ice to get pushed onto land will slow down, creating a jam behind it—which eventually turns into an inexorable wall of moving ice that surges across land, damaging anything and everything in its path. Often ice shoves happen in the spring as the ice starts to break up for the season.


Snownadoes or snow devils are related to waterspouts, and look like a tornado of snow—hence the name. They’re very rare, since they need specific circumstances to form: snow or ice that’s been warmed to the point that it’s steaming, and a column of colder, low-pressure air above the fog. If the rising warm air is caught by a low-level wind shear (a change of wind speed or direction), it will begin to rotate and pick up loose snow. Snownadoes tend to be less intense than tornadoes, but have been reported as wide as nine metres across.

What weird weather phenomena have you experienced?