January is generally cold, with the freezing tramontana wind sweeping down from the north. January 29, 30 and 31 are known as the "giornate della merla" (days of the blackbird) and are supposed to be the coldest of the year.
A winter vacation has some advantages, however: once the Christmas holidays are over (after January 6), the sights are almost deserted and you will find a warm welcome everywhere. In hotels, low season prices apply.
Italians say that February is "corto e maledetto" - short and accursed. It can be almost as cold as January, although winter is traditionally held to be at an end if the weather is good on the Feast of Candlemas (February 2).
Again, tourists are few and far between and cheap flights and hotel rooms abound.
March weather is notoriously capricious: Italians say "Marzo è pazzarello" - March is crazy. It is still chilly, and often windy and rainy too. The days are getting longer, however, and March 21 officially marks the start of spring. During the last weekend of the month, the clocks go forward, giving more daylight for sightseeing.
There begin to be more tourists, particularly if Easter falls early.
In April, travelers begin to flock to Italy. Italians say "Natale con i tuoi, Pasqua con chi vuoi": Christmas with the family, Easter with whoever you want. Many nationals take a city break at Easter, adding to the crowds of tourists from overseas. High season rates are charged at hotels everywhere.
The weather is a little warmer.
May is the month of roses, in Italy, with weather that is warm but not too hot for sightseeing. The major sights are crowded - not only with visitors from abroad but also with Italian schoolchildren, as schools often organize trips at this time of year.
Early June is like May, but later in the month the temperature can rise steeply, particularly in the south. June 21 is the longest day of the year.
Seaside resorts begin to fill up after the schools close in the middle of the month.
July and August are too hot for comfortable sightseeing. Although it is no longer true that everything shuts down in August, the cities are best avoided at this time.
September is a good time of year to visit Italy. Temperatures are beginning to drop and the weather is usually dry. Summer resorts are less crowded after the schools open in the middle of the month.
Autumn officially begins on September 23.
October is the best month of all for visiting Rome: the sunny days are known locally as the "ottobrate romane". In northern Italy and at higher altitudes, however, temperatures may already be quite low, particularly at night. The evenings are closing in and during the last weekend of the month the clocks go back.
November is not generally considered to be a good month for visiting Italy. The days are short and it is often rainy, although rarely very cold. In addition, some hotels and restaurants may close in order to carry out renovation work or allow the owners to take a holiday.
If you do opt for a November vacation, don't miss tasting the new wine ("vino novello") and chestnuts that abound at this time of year.
In December, the cold weather returns: you can forget about sitting outside on the piazza sipping a cappuccino. The days are at their shortest.
With the holiday season, prices begin to rise and hotels to fill up: book early to avoid disappointment.
If you decide to come to Italy over Christmas and the New Year, try visiting some of the less famous sights: you'll see something different and avoid the worst of the crowds.