The icing on the cake is an extra pleasure on top of something already good. That was the icing on the cake, and the icing on the cake was the weather.
The cake has to be good first, which is what people forget when they misuse it for a final blow. Americans sometimes reach for frosting instead, but the shape of the phrase is the same.
1phrasethe icing on the cakeAn extra pleasure on top of something already good.
“Winning was enough, and the crowd singing was the icing on the cake.”
the icing on the cake is a phrase.
Also accepted in games: icing on the cake, cherry on top
Practised in Idioms