What do you think of the names Spring and Summer?

I am pregnant with twins girls and we want to name them Spring and Summer. Our 2 others daughters names are Winter and Autumn, with "normal" flower middle names that they can use when they get older and decide their names are too childish. ;-). We would like to know your opinions on the names Spring and Summer like, individually and not as a group of siblings. If that makes sense? So if you pretend we are having the first child and your opinion on what we want to name her. If you could think of any middle or first names for the girls that would sound nice with Winter and Autumn it would be appreciated! :-) We are just 'brainstorming' right now. Thank you in advance. :-)