Green’s Dictionary of Slang

colder than... adj.

see also under cold as... adj.

In phrases

...a nun’s snatch (also …a nun’s arse)

[1950s+] (US) extremely cold.

...a welldigger’s butt (also …a welldigger’s ass)

[1950s+] (US) very cold.

...a witch’s tit (also …a witch’s titty)

1. [1930s+] of weather, very cold.

2. [1960s] of emotions, very unfriendly.

3. [1960s] sexually frigid.