With it's relatively mild climate, Tuscany is a great place to visit all year round.
Whilst weather conditions do vary from region to region within Tuscany, July and August are the hottest months in the area, where it's not unusual to see temperatures reach 30 degrees centigrade. Certainly, at this time of year, some of the major cities can get almost stiflingly hot as can some of the inland valley areas where it's not unusual to see temperatures over 35 degrees, whilst temperatures tend to stay cooler on the hills. However, in these areas the vast majority of the Tuscany holiday properties managed by Bookings For You have air conditioning to ensure you are nice and cool at night.
If you're not someone who enjoys the heat, then you might want to consider travelling across the Spring and early Autumn. September can still be very hot but as a rule, these months do arguably offer holidaymakers the most pleasant temperatures for sightseeing with temperatures then tending to be more around the high teens and early twenties mark.
Winter is also a great time to visit. Whilst Winter is the time of year that the region sees most rainfall, daytimes tend to be mild with temperatures only dropping at night. There is still plenty to see and do, with many of the festivals actually being held in these months.