消 'to dispel' + 暑 'summer heat' = 'to dispel the summer heat.' Pair with 消愁 ('dispel sorrow') and 消食 ('aid digestion') - 消 X is a productive 'get rid of X' frame.
culture
Classic 消暑 foods include 绿豆汤 ('mung bean soup'), 西瓜 ('watermelon'), and 凉茶 ('cooling herbal tea').
