Looking for a holiday destination this summer? Think you need some sun? Here are some cities that are going to be too hot to visit.1, Seville, Spain.Reaching average summer temperatures of 90°F–92°F, this Andalusian gem is the hottest city in Spain.2, Athens, Greece.This Greek capital city has unbearable summer temperatures soaring above 95°F regularly and has heat waves sweeping over often.3 , Marrakech, Morocco.Marrakech becomes unbearably hot from June to August, with temperatures hitting well over 100°F.4, Dubai, UAE.With temperatures around 105°F from June to September and the extreme humidity, Dubai is a must-avoid destination in summer.5, Phoenix, Arizona.Phoenix, one of the hottest cities in the US, regularly exceeds 100°F, often hitting 110°F.