I heard the phrase "a pop-up shower" in a weather broadcasting on the radio. If I understand correctly, it means a shower might come out of nowhere anytime in the day. But I'm not sure if my understanding is correct.
My questions are whether "a pop-up shower" is a common phrase and what it means exactly? Or I simply misheard it and it should be something else?
According to Macmillan, pop up is a phrasal verb that means:
pop up (phrasal verb) to appear very quickly or suddenly
It can also be used as an adjective. On another Macmillan page, we find:
pop up
computing(adj.) used for describing something that appears suddenly on a computer screen : a pop-up menu
By extension, then, a pop-up shower is a rain shower that appears very quickly without warning. Normally, pop-up showers don't last very long; which is something covered by another definition of pop-up:
pop-up (adj.) Intended to remain open for business only temporarily : The site has been home to many pop-up exhibits and stores
If your weather forecasts says there is a chance of pop-up showers, that means a very brief spell of rain might arrive even when the skies are still blue.
As the other answer indicates, "pop-up" means something along the lines of "surprise" or "unexpected". However be aware that this adjective is not normally applied to things like weather, so it sounds like the weather person is trying to be clever, or is making a joke.
It's easy to understand the meaning of the expression, but the nuance makes it a kind of casual, almost neighborly, to sound like the broadcast is talking to us person-to-person rather than in a serious, factual manner. Weather reports often go for this kind of relaxed attitude, as a contrast with the (often) more formal "regular" news.
A common way to express the same thing, but in a more formal way, is to call these "intermittent showers".
