When a person is extremely craving some pussy from a bitchy woman. AKA the beach refers to the Bitch. Heat is the craving of the bitchy snatch.
This can also mean if a man wants to have sex with any girl, but doesn't want to form a relationship. As the saying goes. "I just want to fuck Bitches!" That would be a prime example of Beach Heat! Random outtings of fucking pleasure!
"Dean has got some Beach Heat tonight."
"Because he just wants to fuck some bitches!"