It is only the afternoon rain, it will be gone before your coffee is

I was on a bench in a Casco Viejo plaza when the sky turned grey. A man sweeping nearby said to a visitor who had just opened a map, "It is only the afternoon rain, it will be gone before your coffee is." It was around three. The visitor looked at the sky and then at the man, and took his coffee inside anyway. The rain stopped before the cup was empty. Back in Brazil we say the forecast is a suggestion, and here the sky seems to keep appointments.