I will let you know about the colloquialism which has been classified as a proverb – “It ain’t over till the fat lady sings”.
First of all, let’s learn as we go along. A colloquialism means a word or phrase that is not formal or literary and is often used in ordinary or familiar conversation.
A proverb is a short, well-known pithy saying that states a general truth or piece of advice.
Basically the proverb in question means that one shouldn’t presume to know the outcome of an event that is still in progress. This phrase is usually used when a certain situation is coming to an end. Therefore I conclude here that it appears to be true for the cold snap to end here that fat lady has to sing. Where do I get a fat lady that can sing?
The phrase also gives warning to everyone that they must not assume that the present state of an event or happening is irreversible and lets us know how the event will eventually end. This phrase is now used mostly in associated with organized competitions especially in sports.
The beginning of it all goes back to the stereotypically overweight lady sopranos singing at the opera. The specific imagery relates to the opera cycle “Der Ring des Nibelungen” by Richard Wagner. In the last part “Gotterdammerung” the fat lady is the valkyrie Brunnhilde, who traditionally is shown as a very buxom lady wearing a horned helmet, holding a spear and a round shield. This part is all about the end of the world of the Norse gods and it really comes to an end after the fat lady sings.