A summer metaphor could be:
"She faded into a sea of flame." This is a metaphor because it is a figure of speech that is not meant to be taken literally. This metaphor could mean that the girl is so warm that it feels like she is falling in a sea of flames.
A simile could be:
"I'm as red as a strawberry!" This is a simile because there is a comparison between 'red' and 'strawberry'. This can be a summer simile because it could mean that he/she is sunburned and his/her skin is red, much like the color of a strawberry.
I hope I was able to help you!