Firenze is a favorite travel destination in Tuscany. It's crammed with art and in the season, tourists. One of the most popular activities is the Brunelleschi's Dome Climb, which always features long lines. It's best done with a good set of legs and a skip the line tour.
Florence can be stiflingly hot in the summer, especially during July and August. Winters are wet; the least rain falls in July, the most in November.
Avoid summers if you can, it's hot and packed with sweating tourists in July and August. That said, there's hardly a time you won't encounter tourists in Florence. If you must go in summer, make hotel reservations early.
Spring, starting in March when the daytime temperatures are starting to rise (and nights are chilly) is a fine time to visit. You can still have freezing temperatures at night in April, but the daytime temperatures can be near perfect. May is probably ideal for the weather, although you'll encounter some rain in 13 days of the month. Fall is another good time to go to Florence. September is still warm, October temperatures are near ideal, and even the first half of November is generally fine, although the possibility of rain is greater then, as you can see from the charts below.
The climate charts below show the historic high and low temperatures and average monthly rainfall for Florence, Italy.
Appartamento Signoria (Apartment)
Novella House (near the Central SMN Train Station)