As Canadians, we’re no strangers to snow––and we often take pride in our natural, snow-making abilities. Most of us know that moisture and cold air are the essential ingredients for snowfall.
But, can it ever be too cold to snow? Many have heard this phrase, but is it Canadian folklore? Or, is there some truth behind it?
The answer might just surprise you.
The truth about ‘too cold to snow’
Here’s the basic ingredient list: For snowfall, you need moisture in the atmosphere. If temperatures are too warm, rain is the likely result.
But, let’s think about the opposite extreme––a temperature so bone-chilling that snow cannot form. That’s a myth. Snow can fall even in bitterly cold conditions, as long as there’s enough moisture and some trigger to lift and cool the air further.
This is where the misconception arises from: As temperatures fall, the air loses its ability to hold significant moisture.
Why frigid air rarely brings heavy snow
Cold air is dry air. When temperatures plummet well below freezing, the atmosphere loses the capacity to hold water vapour. This is eloquently explained by the saturation mixing ratio––the maximum water vapour the air can hold. Here’s how it looks:
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0°C – 3.83 g/kg
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-10°C – 1.79 g/kg
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-20°C – 0.78 g/kg
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-30°C – 0.32 g/kg
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-40°C – 0.12 g/kg
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-50°C – 0.04 g/kg
As you can see, the colder the temperature, the drier the air becomes. It effectively highlights why the most extreme snowfalls tend to occur near 0°C, when the air is cold enough to snow heavily, but still warm enough to hold substantial moisture.
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When to expect the heaviest snowfall
If you’re reading this, chances are you’re a snow lover. So, when can you expect the biggest snowfall? The”Goldilocks zone” for heavy snow sits just below the freezing mark. Here, the air is warm enough to hold plenty of moisture but still cold enough to produce snow.
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Snow in Earth’s coldest places
Let’s test this in the most extreme environments on Earth, like Antarctica, where snowfall becomes extraordinarily rare––not because it’s “too cold to snow” but because the air is bone-dry.
Take the Dry Valleys, for example. These regions are practically snow deserts, where snowfall is nearly non-existent despite temperatures being cold enough to allow it. It’s the lack of moisture that makes snowfall in this region nearly impossible.
Never say never
So, can it ever be too cold to snow? In short, no. While the chances of snow steadily decrease as temperatures drop, there’s no magical threshold where it becomes impossible to snow.
So next time you find yourself in a frigid environment, you can bust the myth and impress your friends with the snow science to back it up.
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Header images courtesy of Getty Images. Credit: Andrey Haymin / 500px.