How Much Does Snow Weigh? Powder vs Wet Snow by the Cubic Foot

A cubic foot of snow weighs roughly 3 to 7 pounds (1.4 to 3.2 kg) when it is light, dry powder, and roughly 15 to 20 pounds (6.8 to 9 kg) when it is heavy, wet snow. Water itself weighs about 62.4 pounds per cubic foot (28.3 kg), so snow’s weight depends on how much of its volume is ice and water rather than air.

Fresh snow that falls in ordinary winter conditions usually lands somewhere between those extremes, at around 5 to 10 pounds per cubic foot (2.3 to 4.5 kg).

Why does snow weigh so much less than water?

Snow is mostly air. Fresh flakes pile up loosely, with gaps between the crystals, so a cubic foot of fluffy snow holds only a small fraction of the water the same space would hold as a liquid. Melting a foot of powder can leave only an inch or so of water, while a foot of wet snow can leave several inches.

Meteorologists describe this as the snow-to-liquid ratio. A ratio of 10 to 1 means 10 inches of snow melts into 1 inch of water, and it is a common rule of thumb for average snowfall. Ratios of 20 to 1 or higher describe light powder, and ratios of 5 to 1 or lower describe heavy, wet snow.

What makes snow fluffy or heavy?

Temperature decides most of it. Very cold air holds little moisture and produces small, dry crystals that stack loosely. Snow that falls near freezing carries more liquid water, and its flakes clump and compact as they land, which makes it dense and sticky. The reasons snow forms at all at certain temperatures are covered in how cold it has to be to snow.

Several other things add weight after the snow lands:

• Rain falling on a snowpack soaks in and raises its weight quickly.
• Partial melting and refreezing turn the surface layers into dense granules or ice.
• Time and the snow’s own weight compress older layers.
• Wind packs snow tightly, especially in drifts.

How much does snow on a roof or driveway weigh?

Multiply depth by area to get volume, then multiply by the density. One foot of snow over 1,000 square feet (93 square meters) is 1,000 cubic feet. At 3 to 7 pounds per cubic foot, that is about 3,000 to 7,000 pounds (1,360 to 3,175 kg). At 15 to 20 pounds per cubic foot, the same layer is about 15,000 to 20,000 pounds (6,800 to 9,000 kg).

These are estimates, because real snow varies layer by layer. They show why the same depth of snow can be a light nuisance one week and a heavy load the next.

When is snow on a roof a problem?

Roofs are designed to carry a snow load that depends on local building codes and climate, and most carry normal snowfalls without trouble. Wet snow, rain on top of snow and long stretches without melting raise the load fastest.

Warning signs include creaking or popping sounds, new cracks in ceilings or walls, doors and windows that suddenly stick, and visible sagging. If you see them, leave the area and call a structural engineer or the local building department. Climbing onto a snowy roof is dangerous, so hire a professional for roof clearing.

How heavy is a shovelful, and is it safe to shovel?

A shovel holds far less than a cubic foot, but the weight adds up over a whole driveway, and wet snow can be several times heavier per scoop than powder. Shoveling is hard exercise. The Centers for Disease Control and Prevention (CDC) and other health agencies warn that cold weather and heavy exertion strain the heart, so people with heart conditions or little regular activity should ask a doctor before shoveling. Pushing snow instead of lifting it, taking breaks and stopping at chest pain, dizziness or shortness of breath are standard advice, and chest pain calls for emergency help.

Forecasts that mention snow totals, snow-to-liquid ratios and rain mixing in come from the National Weather Service. Storms that bring thunder and lightning with snowfall are explained in what thundersnow is.

Quick answers

How much does a gallon of snow weigh?

It varies with density. A gallon is about 0.13 cubic feet, so it weighs under a pound for most fresh snow, from a few ounces for powder to a little over 2 pounds for packed, wet snow. A gallon of water is about 8.3 pounds (3.8 kg).

Is wet snow always heavier than powder?

Yes, for the same volume. Wet snow holds more liquid water and less air, so each cubic foot weighs more. A deep layer of powder can still weigh more in total than a thin layer of wet snow.

Does snow get heavier after it falls?

It can. Rain, melting and compaction raise its density, so a snowpack often weighs more a few days after the storm than it did when the snow stopped.