Dining outside is one of the great pleasures of Rome. Combine exceptional food with Rome's outdoor atmosphere, part busy and part laid-back, and you will surely end up with a fine night, or lunch, out. The weather in Rome is pretty dependable from spring to fall, and should hold up if you like your tables outside from at least May to September. In summer, eating outside at lunch can be quite hot, but the evenings are absolutely perfect. Though restaurants with outside seating might seem the norm in a city where the weather is as mild as Rome's, this isn't always the case and ending up at a place with both great food and a table under the stars should not be left to fate. These restaurants are often sought after and it would be wise to book an outside table well in advance.
The two types of outdoor dining are street-side and private, either in a piazza or courtyard. The best is the latter if you do not like your dinner with a side of passing cars, and the best of these are Da Teo in Trastevere, Cesare Al Casaletto (Monteverde), Necci dal 1924 (Pigneto) and Flavio Al Velavevodetto (Testaccio), which has seating on the roof. Street-side dining is often more hectic, like the restaurants themselves, but have the benefit of being where the action is. The pizzerias in this list all fall under this category, as does L'Asino D'Oro (Monti). If you're looking for outdoor dining to beat all outdoor dining in Rome, then head to Vivi Bistrot, which you'll find in the pristine Villa Pamphili park.