Faire un froid de canard

When it’s really, really cold, it’s a duck’s cold, according to the French idiom il fait un froid de canard. The expression is very common and may be used in any circumstances to express that the temperature is, well, freezing cold.

Note that il fait is the expression that introduces weather expressions in French. Instead of the English It is (rainy, sunny, etc.), the French language speaks of what the weather is doing.

Which begs the question, what is it exactly that the weather is doing to ducks for them to be forever associated with brass monkey weather?

Origin

The expression comes from duck hunting and has been in use in the French language for times immemorial. If you've ever been on a duck hunting expedition, you know that the best duck hunting days are in winter. You also know that the adventure consists of standing in freezing waters for extended periods of time, waiting for the feathered creatures to get close enough to be shot. Thus, that bitter cold that seeps into the bones is known as un froid de canard.

Interestingly, the cold impacts ducks' quality of life too, although in a different way. Ducks' natural habitat for the major part of the year is ponds and lakes, where a large body of water offers some protection from terrestrial predators - such as humans. When ponds freeze, the birds are forced to move to streams and rivers, less prone to frost. That very move makes them more vulnerable to hunters who can easily spot them and hide from them. In other words: the colder the day, the higher the risk of getting shot if you happen to be a duck.

Examples

Mets ton bonnet; il fait un froid de canard!

Put your hat on; it's freezing cold!

Quel froid de canard! L'étang a gelé pendant la nuit.

It's so cold! The pond froze overnight.