I do not know what the picture is about.
They are close - so it depends on what your idea is.
#2 sounds like the dream is beautiful and is about summer. So for example you could have a beautiful dream about summer, even in the winter !
# 3 sounds like a dream you had in a beautiful summer. The dream could be about summer, but does not have to be.
Hope this is not too confusing.
Probably all 3 are roughly ok