What makes snow heavy? It’s all about the snow ratio

Experts warn of health risks associated with shovelling snow. Jan. 16, 2026 (Josh Marano/CTV News Ottawa)

Many Nova Scotians spent Monday morning shovelling to clear out the 10-to-30 cm of snow that fell overnight.

This snow is wet, compact, and heavy by weight – certainly not the fluffy, light powder one would love if hitting the ski hill.

So, what makes for “heavy” snow?

The answer is simply how much liquid water each centimetre of snow melts down to. You see, that ratio – snow ratio – isn’t constant. It can, in fact, vary from a very low ratio (heavy, wet snow) to a very high ratio (fluffy powder) not only from system-to-system but from the same system over a large enough area.

The standard snow ratio is taken as 10:1 – that is 10 mm of snow (1 cm) melting to 1 mm of water. A “heavy” snow is typically at a ratio of less than 10:1.

For the current system, some ratios in Nova Scotia were as low as 7:1 or 5:1, making for heavy, wet snow. A few parts of the Maritimes experienced a “fluffier” type of snow.

The ratio in the area of Prince Edward Island, southeastern New Brunswick, and Nova Scotia’s Cumberland County observed as being more 16:1 – 20:1, as in taking 1.6 – 2 cm of snow to melt to 1 mm of water.

So, what dictates snow ratio? Typically, it’s the temperature profile of the atmosphere from the surface to the snow-producing cloud. The closer to zero (freezing) that column of air is, the “wetter” or “heavier” the snow tends to be. A colder column of air, however, favours a higher snow ratio and hence a lighter, fluffy snow that adds up more per millimetre of water used to produce it.