How heavy is snow?

by | Feb 23, 2024 | Calgary, Snow

So just how heavy is snow?

Snow is generally light and fluffy, but with time, accumulated snow can be quite heavy! Snow weighs approximately 20 pounds per cubic foot when settled. This is about 320 kg per cubic meter.

Snow is generally much heavier when it is settled, as the pressure from snow above leads to compact the snow below. This is the weight of saturated snow, and can be used for most worst case scenarios of analysis for impact of snow on structures, such as your home roof!

Key Facts about Heavy Snow:

  • Calculation for snow weight: S x 1.25 =P (where S = depth of snow in inches, 1.25 = approx. weight of 1 sq ft of snow each 1” of snow, P = lbs/sq ft)
  • Always factor in ice into snow weight.
  • The shape of snow affects the weight!
  • Snow weighs about 20% of what water weighs
  • Warmer winter temperatures create heavy snow.
  • The same temperatures that create heavy snow can create ice dams.
  • On average two feet of snow can equal around 19 tons of weight on a typical residential home roof!

What types of snow are there?

Typically snow can be categorized into the following:

Wet Snow: This is dense, sticky snow, which usually occurs in warm temperatures with low wind conditions. In Calgary we can get wet snow during Chinook season.

Dry Snow: Dry snow  is common and occurs when the surface air temperature is below freezing. It lacks the stickiness of wet snow.

Sugar Snow: This snow gets it’s name from the formation of larger snow crystals. This snow is easy to crush and forms when water vapor freezes onto existing snow crystals.

Settled Snow: Typically snow can be considered as settled snow when stays in place for more than one day. As more snow accumulates the density of settled snow increases.

Wind-Toughened Snow: Wind has an adverse effect on snow drifts, causing snow to become hardened on the outside.

Firn Snow: This is granular, and highly-compacted icy snow. This isn’t typical snow! It is generally old, a year or more, and gradually transforms to glacier ice.

Slush: This is a mix of snow and melting water. If temperatures fall well below zero then the slush mixture can freeze.

What makes snow heavy or light?

Water moisture content in the snow makes it heavy. Wet snow is far more of a concern for structural capacities of buildings and structures than other types of snow. This is because the moisture content trapped in the snow increase the density and weight.

Light snow is generally going to fall in colder temperatures. Ice crystals will form quicker due to extreme cold temperatures.

Heavy snow forms when temperatures allow for the accumulation of denser snow, with higher unfrozen moisture content. You can identify heavy snow by the way it falls, it just falls faster than light snow.

What type of snow do we get in Calgary?

Generally Calgary has colder winter temperatures than other areas. Meaning snow crystals will form more quickly due to the extreme cold, and so snow will be light and fluffy. However in certain conditions such as chinooks or warmer parts of winter and with the right air humidity Calgary can get heavy snow. Calgary is well known for varying temperatures in winter, swinging from extreme cold to up to 10C° in the middle of winter! This means Calgary can get a mix of heavy dense snow and light fluffy snow.

Also, with Calgary’s long winters, snow gets the chance to accumulate. Winds are also prevalent. This means snow accumulation will result in hard packed wind swept drifts, not fun for Calgary snow removal. Luckily there are many high quality Calgary snow removal companies at your disposal to ensure your property clean and clear of snow for the winter season.

Is heavy snow dangerous?

In moderate quantities heavy snow is not dangerous. If left to build up, such as snow on a roof, then it can indeed be dangerous. In larger quantities accumulated snow can cause structural failure of a roof system, break tree branches, or even down power lines.

Heavy snow accumulation with progressive snow melt can also cause water damage. Specific concerns are for ice damming and around foundation of buildings. Gutters are also at a risk, if not cleared in time.

Can I calculate the weight of snow?

You can!

Our article “Snow on a Roof – How much snow can safely be on a roof?” serves to explain how to calculate snow weight for the most common or at risk condition, which is on a roof.

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