Answer:
This Isn't a metaphor
Explanation:
Metaphors are used not to compare but to add exaggeration.
Even though there isn't "like" or "as" in the text he still uses the word compare in a context where you can infer he knows she is indeed not the summer's day, but could be describe as such.
Metaphor ex: My face became a tomato as my classmates laughed at me.
Slimily ex: My face was as bright as a tomato after hearing the mocking laughter of my class. I could be more embarrass, I internalized with my eyes stuck to the floor.
Similes compared to things. Metaphors do not.
