Eleven creepy books set in summer

At Bustle Emma Oulton tagged eleven "scorchingly scary novels set in the summer heat," including:
The Marsh King's Daughter by Karen Dionne

Helena was born in captivity, in the cabin where her teenage mother was held for years against her will by Helena's father, a man she loved and feared in equal parts throughout her childhood. Years later, Helena is free and living under a false name — until