Sightseeing: spring and autumn are the best seasons for visiting historical places because the weather is mostly mild and pleasant, and crowds tend to be thinner than in the summer months The early spring and late autumn are colder and with more unpredictable weather towards the north. Fall is when the harvest takes place, as the countryside bursts into colour and Italians around the country celebrate their incredible food and wines with vibrant festivals. Tuscany, Le Marche, and Piedmont are great places to experience the harvest and truffle festivities.
Hiking and other outdoor activities: from mid-June to August is weather is typically reliably sunny and stable, but also warm to hot depending on the region, so it may not be the best time for Cinque Terre, the Amalfi Coast, Sicily and Sardinia, and other scenic areas where weather is considerably hot. May to June and September to October are the perfect time in these warmer areas of the country. In the Dolomites and the Italian Alps, the best time is typycally from mid-June through to early October, since snow and rain are common during most of the spring. In the lakes, such as Como, Maggiore and the Garda the temperatures are mild all year, despite having the Alps as a background, rarely dipping below zero in winter, so spring and autumn are ideal times to visit.
Snorkelling and Diving: diving in Italy is one of the best in Europe with famous diving spots such as Portofino marine reserve and famous dives such as Baia underwater archaeological park. Italy is a great destination for scuba divers who love archaeological diving and groupers. The best time of the year is typically from late May to late October.
Beaches: from mid-June to mid-September is typically prime beach season in the whole country although August can get extremely busy with locals. Early June and late September may also offer very pleasant conditions to enjoy the beaches that Italy has to offer, particularly in the south, Sardinia and Sicily.
Winter activities: from December to late March, you can find the best season for skiing and other outdoor winter activities, for which the Dolomites and the Italian Alps are a top destination in Europe.
Mount Etna: can be visited and hiked all year long, but the best months to visit is when temperatures are pleasantly warm, and crowds will be not extreme, this is May and June or late September and October.
Sicily: the best time for exploring historical places is from April through mid-June or mid-September through October. The official beach season begins in June. However, the sea is usually warm enough for swimming in May, so those who want to enjoy it without the crowds may want to come then, especially during the latter half of the month. September, and often October, can also be ideal as the sea will not have cooled much yet many of the tourists will be gone.
Vatican: the best time to visit the Vatican is between after eastern holidays until mid-June, then from mid-September to November. Crowds are less dense during this period. Avoid summer if you can, hot temperatures of Rome in summer make queuing particularly uncomfortable. Likewise, avoid Christmas. I would like to add some tips for visiting the Vatican: Book your Vatican Museums tickets online, is not necessary to be one of those people waiting outside the Vatican Museums in a three-hour line. Book your ticket in advance online at the at the Vatican website. Note that because it is a religious institution the Vatican is closed most Sundays, and on other holy days. It is free on the last Sunday of the month, but we recommend avoiding it then as it becomes even more crowded.
San Marino: the best time to visit San Marino is from April to June or from mid-September to the end of October. During these months, the temperature is most pleasant.