Here in the suburbs of the Yankeestanian capital (Здесь в пригородах пиндостанской столицы), it's "cold as a witch's tit" (так холодно, как сиська у ведьмы), but not yet "cold enough to freeze the balls off a brass monkey" (достаточно холодно, чтобы отморозить яйца/муда с латунной обезьяны).



P.S. Speaking of witches and their ta-ta's, it's interesting to do a Google Image search with ведьма, and then compare the results if you use колдунья instead (the words can both be translated as "witch" -- yet they're not quite synonymous!)