Tuscany encompasses many diverse terrains and landscapes and the weather conditions can vary from one zone to the next.
You can be sure that July and August in Tuscany will be very hot which can make Rome and the major cities of Tuscany veritable hothouses and the sunflowers are out in abundance. This very hot weather is supposed to break around the day of feragosto in the middle of August when the first rains are expected and with them a beginning of a decrease in temperature but this hardly ever happens! September can still be very hot with October being a fine month to visit Tuscany - blue skies without the packed cities and the intense heat and of course it is grape harvesting time.
November sees night time temperatures really begin to drop with crisp autumn days to accompany the main olive harvest throughout Tuscany. Winter in Tuscany can be cold and wet but spring always seems to come quickly. March is azalea and camellia time and can be quite cool with it hotting up during April, May and June.