When to Go
If you don't have to go to Rome in July and August, don't. It's way too hot. Italians know this. That's why they abandon the city in August, especially late August, and head for their vacations in the cooler countryside or maybe the mountain or coastal areas. If you're thinking that that means Rome will be less crowded, don't forget to take in consideration all the other tourists on their summer vacations. Rome is a walking city so, if you're not acclimated to summer heat, think twice before embarking on a sightseeing vacation in the middle of summer. The excessive heat can quickly mar your vacation, limiting you to only early morning and late afternoon excursions. Those with health problems should especially take note.
April, May, September and October offer the mildest weather with the lowest precipitation so, of course, they are popular with tourists. Bitter winters are rare in Rome but rain isn't so you'll have to decide if carrying an unbrella and wearing an overcoat is a price you're willing to pay to dodge the other tourists. The average precipitation in November is 4.4 inches (111.8mm). December, January and February continue the wet trend with precipitation averaging each month from 3.0 to 3.5 inches (76.2 to 88.9mm).
Average Monthly Temperatures in Degrees Farenheit (and Celsius)
January
Average high is 55 (13).
Average low is 38 (3).
February
Average high is 56 (13).
Average low is 39 (4).
March
Average high is 59 (15).
Average low is 42 (6).
April
Average high is 64 (18).
Average low is 46 (8).
May
Average high is 71 (22).
Average low is 53 (12).
June
Average high is 78 (26).
Average low is 60 (16).
July
Average high is 83 (28).
Average low is 64 (18).
August
Average high is 83 (28).
Average low is 65 (18).
September
Average high is 78 (26).
Average low is 60 (16).
October
Average high is 71 (22).
Average low is 53 (12).
November
Average high is 63 (17).
Average low is 46 (8).
December
Average high is 57 (14).
Average low is 41 (5).