You do not have to ignore the weather conditions or the months when visitors flock to the city's landmarks before reserving your hotel accommodations in Rome.
Rome enjoys pleasant weather, making it possible to visit the eternal city all year; nevertheless, spring and fall are without a doubt the finest seasons to visit, with usually clear sky and moderate temperatures (even if late autumn, November, can be rainy). July and August are humid and hot (many Romans leave the city in August, thus many businesses shut); December to February have fiercely chilly weather, but it's seldom dark and dismal.
In general, the tourist season in Rome runs from April 1st to October 31st, with an additional two weeks around Christmas and New Year's Eve.
August is a great month to visit Rome since it is quiet and you can explore the eternal city's attractions, such as the Vatican and old Roman ruins.
During Holy Week (Easter), Catholics from all over the globe make pilgrimages to Rome's different basilicas to hear the Pope offer his blessing from the window of its apartment in sixty languages. On Good Friday, the pope leads a procession of the Cross from the Colosseum to Capitoline Hill, which is live-streamed across the globe; no tickets are required to see it.
Making a reservation at a Rome hotel during the Easter season is very difficult, and you may find yourself having to alter your hotel room often owing to the overbooking system.