If you are planning to stock up on wine while in France, the nationwide Foires aux vins (wine fairs or wine sales), a twice-yearly event in spring and autumn, are a major date for your diary.
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During these periods, wines are on sale at heavily discounted rates at supermarkets all across the county. They can vary from modest everyday wines to more exalted vintages; all price ranges are represented.
You'll see a small number of overseas wineries represented too. (By the way, these Foires aren't to be confused with the various traditional open-air wine harvest festivals held in Provence throughout the autumn.)
Stores can achieve up to 15 per cent of their annual wine sales during their Foires and the bigger ones go all out to create a party atmosphere.
Sometimes they lay on free nibbles and make sure that their wine buyers are on hand to advise customers. It's a good idea to fix your budget before you go along, as it's only too easy to get carried away and spend far more than you planned.
The Foires aux vins aren't fixed feasts and the dates and duration vary from supermarket to supermarket. In autumn they're held to coincide with the grape harvest festivals.
Some outlets start in the last week of August, others in October. But September is the best time to catch the Foire at a wide range of stores.
The spring Foires - which are much smaller - tend to be in March, with some spilling over into April, depending on when Easter falls.
The Foire at an individual store can run from anything from a single long weekend to a full month.
The autumn sales have the heavy-hitting wines and are the best time to snap up a meaty vintage Bordeaux or Burgundy as a special treat for Thanksgiving, Christmas or New Year.
The spring ones have the upcoming season of weddings and summer picnics in their sights. They're more likely to be dominated by whites and lighter reds.
Plus the essential vin rosé de Provence, which should generally be drunk young and will be represented by the previous autumn's vintage. Champagne never goes out of season, of course.
Even the national supermarket chains stock a good range of local food and wine, and this varies widely in stores from region to region. So you're bound to find a decent line-up of Provence wines at the Foires in Provence.
The Leclerc supermarkets first had the original idea of doing this back in 1973. They are generally regarded as still staging the best Foires aux vins, though this particular chain holds them in autumn only.
In any case it's always useful to visit several stores and compare the promotions, if you have time. Many offer a "seven bottles for the price of six" or other similar deals at this time, which can be very good value. Various wine retail websites such as Mondovino or Wineandco also get in on the act.
A word of caution: the Foires can also often be a way of selling hard-to-shift second-rate wines which have been languishing on the shelves for too long, and so caution is required.
Real wine snobs only buy from a caviste (wine merchant or cellarman), and look down their finely developed noses at the mass-market Foires.
But this is certainly not to say that, whether you're an oenophile or an ordinary consumer, you can't find some modest bargains. Some stores hold congenial preview evenings - soirées inaugurales - with advance tastings of some of the bottles on offer, and a chance to buy them ahead of the rush.
Locals keep an eagle eye out for these, and queue outside supermarkets on the morning of the first day of the sales themselves. It's not unusual for an exceptional wine to fly off the shelves within hours.
If you read French and are planning on some serious wine buying, it's well worth checking out both national and local newspapers and magazines such as La Revue du Vin de France, which publish special issues reviewing the most interesting wines and keenest prices in the weeks running up to the Foires.
After the wine sales start, the larger supermarkets should, as mentioned above, have a buyer on the shop floor, to help you choose.
But we've found that in Provence, where people are rarely too busy to stop and chat, even the assistants at our neighbourhood discount store will be happy to take a moment or two to talk about their wines and share their non-expert - but nonetheless passionately held - opinions.