We stayed in mid August and the weather was in the mid to high 30s. However, Italy had just come out of a major heat wave so this may have been hotter than usual for the time of year. I found the heat OK, but my husband likes it cooler. The house was great for him as it remained remarkably cool in this heat even without any air conditioning.
I naively was surprised by how narrow and winding the roads got as we neared the farmhouse the first time, but as I got to know the area over the week it seemed so obvious that they would be like that. If you are planning to hire a car (which I'd recommend), and are not used to driving abroad, don't go for anything too big as you need to pass in some tight places on occasions and carry out 3 point turns - all of which feels harder when driving on the right, in an unfamiliar car with gears on the right.
I spent a couple of days lazing in front of the farmhouse, whilst my 6 year old was able to play happily inside in the cool. There's a large box of toys which he and his cousin (also 6) worked their way through during the week.
We did try walking up to Vellano without using the main road, but this turned out to be a very muddy, difficult route. Luckily there was a tap in the village where we could clean ourselves, and we hadn't been wearing anything too smart, so no damage was done - plus we'd had a good laugh as we'd scrambled up wondering what we must look like to the locals. However, after that we walked to Vellano via the road, which took 40 mins, and has some lovely views along the way, so is in no way a bad alternative.
We ate in the village a few times and went down to Pescia one evening for a meal. We also cooked at the farmhouse, which had plenty of pots, pans, crockery, cutlery, etc...
The only thing that could have made the place better would have been a paddling pool of some kind (there might have been one there that we just didn't find). There was a space to the right of the front door where we could have placed it in the shade and we could have cooled off in it after being out and about. Had we found one in a shop we would have bought it, but we didn't see any on the rare times we went shopping.
All in all, we had a great week!
