August - Sarria to Santiago

It can be wet anytime in Galicia but August can be very hot so you might have beautiful weather for the week that you will be walking.
I found the 114km from Sarria to Santiago surprisingly strenuous with many undulating paths of short, sharp uphills and equally short, sharp downhills. However, there are no mountains so you won't be scrambling! You will walk through very pretty countryside with small subsistence farms, stone walls, forests and quaint stone villages. You'll be in dairy country so the overpowering perfume is sickly sweet cowshit, and mixed with mud it can be lethal!
There are many albergues on this stretch, both municipal and private, but they will be crowded in August. You could phone ahead of time and book beds in the private albergues. A few municipal albergues won't accept pilgrims who have walked less than 20km so if you start in Sarria you might have to walk to Portomarin on your first day.
Have a great walk - and don't rush it - it will be over before you know it.