It's so cold ...
It's colder than a gold digger's heart.
It's colder than Jack Frost's toes after he skates on an icy pond.
It's colder than a brass toilet seat on the shady side of an iceberg.
It's so cold the dogs are sticking to the fire hydrants.
It's colder than a witch's belt buckle.
It's colder than a day-old dumpling.
It's colder than skinny dipping in a snow storm.