Heavy July rainfall has prompted Bordeaux winegrowers to revise their harvesting predictions yet again.

Hot and dry conditions throughout the spring had many growers concerned about the highly advanced growth stages of their vines last month.

The March-May water deficit in the region was 55 per cent - the highest since the 46 per cent recorded in 1976.

As a result, the general consensus in Bordeaux - as well in the Rhone Valley, Burgundy and Champagne - was that harvesting would have to start earlier than had been considered for 200 years.

However, Decanter now reports that heavy rain showers and cooler temperatures throughout July have slowed the progress of the vine development.

While Bordeaux harvesting is still likely to occur ahead of the traditional schedule, it is expected to take place in early September.

Christian Seely, head of AXA Millesimes, which owns Pauillac estate Pichon Longueville-Baron, explained: "A month ago we thought it might be two weeks early. May and June were alarmingly hot and dry.

"Over the past few weeks we have had some cooler weather and some rain and that's why we can put the date back a bit to one week early."

However, growers in the Rhone and Champagne are planning to pick their grapes early.

"It will be one of the earliest harvests in history due to a summer-like spring. It should start around August 22nd," said Frederic Rouzaud, president and chief executive of Champagne Louis Roederer.

Meanwhile, the hot and dry spring in Douro Valley appears to have done irreparable damage to the grapes of vintage port growers.

Symington Family Estates viticulturist Miles Edlmann recently revealed that his vineyards had experienced some of the worst some sunburn in living memory.

This was then followed by brief hail showers that further damaged the delicate grapes.