don't worry: no harm is being done! This opposed to the short heat spike end of july (2 days at 35-36°), that burned up to 50% of the grapes in some plots.
This time round, no negative effects: véraison (colouring of the grapes) is advancing steadily, which means that the grapes have become much less prone to get sunburned. As there is plenty humidity in the subsoil, there is no heat stress for the moment. Finally, this prolonged spell of dry weather - the first this year - has calmed down mildiou & friends.
Early maturity reports (based on chardonnay and gamay grapes from the maconnais) show a very quick development of grape maturity, with a 2% alcohol increase in just 5 days. The explanation is excellent conditions and low yields (due to bad conditions during flowering and mildiou attacks).
The harvesting date seems to be in line with the 2008 & 2010 vintage, maybe somewhat earlier if the good weather holds.
Personally, I think we might be in for a surprise in terms of quality. As of today, no sign of any grey mould yet, the (few) remaining grapes are perfectly healthy and happy.