South Italy, where Pompeii is located, sits in the middle of the Mediterranean Sea and hence, the weather can be quite warm the whole year round, except for the winter months. As most of the time will be spent outdoors in Pompeii exploring the excavations, going during summers is not a good idea. Spring and Fall are the best times to travel here. If you travel during the winter, you need to keep in mind that the week of Christmas can be extremely crowded in lieu of Christmas. The month of August can also be avoided as most Italians are on vacation.