Under the Final Moon (Underworld Detection Agency #6) by Hannah Jayne

It's not the end of the world--until it is. Sophie Lawson may be a mere human with no special abilities except a strong immunity to magic. But the havoc she's wreaked on the supernaturals who come up against the Underworld Detection Agency have earned her plenty of enemies. Still, a girl can't freak out every time a horribly barbecued corpse is found with her business card in its hand. Or see a sudden glut of earthquakes, wildfires and three-headed dogs as just another day in California. But Alex Grace, her favorite fallen angel, is concerned--or saying he is to see more of her. Getting Sophie to see all the signs of the Apocalypse is an interesting way to heat things up. Or maybe what's making everyone hot under the collar is the fact that all Hell is about to break loose. . .