Rome: Strategies: When to Go
Spring and fall are the optimum time to tour Rome. The days are warm and sunny, so visitors can take advantage of the many outdoor cafés and restaurants with terraces. Summer is notoriously hot, and while fewer Romans are fleeing the city during the most torrid months of July and August, it really gets too warm for an extended enjoyable stay. Most hotels have air-conditioning now, but much of what tourists come to see is outdoors (and if you do come then, you’ll learn why many places shut for an afternoon siesta). On the other hand, Rome in December is magical, with Christmas lights on many of the major streets and most churches displaying extravagant crèches, so keep it in mind for a holiday escape.
— Elizabeth Helman Minchilli 06/20/2007