It’s easier in summer to wear lots of colours as you don’t have to layer so much, but if I have to choose four, I’d go red, cream, navy and hyacinth blue (not worn at the same time as red).
I certainly have plenty of summer things, Floradora9, and they do usually get worn a lot. Still waiting at the moment, though - the sun is lovely but there’s still a wind that apparently comes straight from the North Pole.
I suppose it will depend to some extent on where you live, though. I once shared a house with a girl from Glasgow who said that back home she never wore actual summer things - just fewer winter ones.