Planning for next years' vacations... Barcelona Spain and Florence Italy. Which month is best for Florence? (and Barcelona if you have that advice too!)
In terms of crowds, I would rank Florence as least crowded in November/December, second least crowded in April/May and most crowded in September. The least crowded months also have the higher likelihood of rain, but I don't consider that a major downside.
I agree, September is the most crowded for Florence and most of Italy.
We went to Florence and Tuscany two weeks before Christmas 2 years ago. I can't compare to other times of the year, but we enjoyed the smaller crowds. We took two Walks of Italy tours, which I highly recommend. One starts first thing in the morning with a visit to David and continues to the Duomo and the heart of Florence. The other is their tour of the Uffizi. We had skip the line tickets to the Accademia and Uffizi. Even in December, by 9:30 the line at the Accademia was pretty long.
Florence proper was not very crowded and we had our agriturismo all to ourselves! The weather was nice. Morninngs were sweater weather but it got up into the 60's most days. There were a couple of days of overcast, one day of late afternoon drizzle but the rest of the time was brilliant sunshine!
Another vote for December.
We were there for a week in December a couple of years ago and for the whole month of September last year. Huge difference, even though for both trips we were staying in very untouristy neighborhoods AND we had real air conditioning in our apartment and daily classrooms all during the boiling hot September.
November is actually our number one favorite time to go to Italy (October WOULD be except that we can't bear to miss October in Minnesota).
“Best” is a subjective attribute. It depends on what you want. The weather or the crowds may be a factor in your choice.
Below are the tourist figures for Florence in 2017, by month.
http://www.cittametropolitana.fi.it/wp-content/uploads/citta_metropolitana_per_mesi.pdf
Alberghi=hotels
Extra Alberghi=accommodations other than hotels (house rentals, campgrounds, etc.)
Italiani=Italian tourists
Stranieri=Foreign tourists
As you can see January and February are the least crowded.
April through October is crowded. June through September most crowded.
November and December is less crowded.
If weather is a factor, both Florence and Barcelona are cold in Nov/Dec. I used to visit both cities every year at Thanksgiving (brother in law lived in BCN, my relatives in Florence). Some years temperatures dropped below freezing at night, other years it was more bearable, but never beach weather.
September is generally hot, although sometime you get some short but heavy summer storms that cool the place a bit.
April/May is cooler than September, but spring is hard to predict. Some years it can be warm, some years cool and damp. May is warmer than April, generally.