So I walked back to my room and collapsed on the bottom bunk, thinking that if people were rain, I was drizzle and she was a hurricane.

This quote compares the speaker’s personality to rain and someone else’s personality to a hurricane. The speaker is saying that they are calm and subtle (like drizzle) compared to the person they’re thinking about, who is powerful and intense (like a hurricane). The speaker is walking back to their bedroom, and has a lot on their mind; they are reflecting on how different their personalities are from the other person.