Please be aware that Rome has multiple airports and that these results are for all airports serving the city.
The best month to arrive at Rome is January and the most expensive month to fly is December. (Average prices, based on 617 datapoints.)
The best day to arrive at Rome is Wednesday and it would be best to avoid Saturday, as prices are on average 62.86% higher than on Wednesday. (Average prices, based on 277 datapoints.)
The cheapest airline flying to Rome is Vueling. They are 79% cheaper than Lufthansa. (Average prices, based on 686 datapoints.)