It's crunch time in the vineyards of France, as the world's most highly prized grapes are harvested at last. But will 2007 really be a vintage year?

Dawn breaks over Burgundy's Côte d'Or, the aptly named Golden Slope whose vineyards rise like a massive wave from the Dijon to Beaune road. Within minutes, groups of pickers can be seen working their way up and down rows of vines, carefully harvesting some of the most highly prized bunches of grapes in the world. Among them this year is the artist and illustrator Lucinda Rogers, whose wonderful drawings accompany The Weasel column each week in these pages, and who is visiting two famous growers, Roumier in Chambolle Musigny and Méo-Camuzet in Vosne Romanée, to sketch the gathering in of the harvest.

The vines are low and close together here, and the bunches of pinot noir grapes are not trained to sit neatly on the vine as they often do in the New World where the vineyards are set up for mechanisation. The harvest is tiring work for the families who tend these vineyards. As they move steadily along the rows, they are constantly bending to cut the bunches, often sticking a hopeful hand inside or round the back of a leafy vine to cut a wayward, half-visible bunch, occasionally nipping themselves in the process. Once the bucket is full, it's emptied into a bigger one on a stronger back, which tips up its contents into the waiting trailer.

By midday, the pickers are tired and hungry, but at last they can stop, relax and enjoy the benefits of a traditional French two-hour lunch break. France may be a fast-food nation in some ways, but the pickers' lunch is one tradition that small growers like Roumier and Méo-Camuzet will never abandon. Time for a hearty casserole or plate of grilled sausage back at the cellar, or in the vineyard if the cellar is too far. Washed down by a welcome glass of the grower's own bourgogne rouge, this precious time off to chat, laugh and celebrate food, wine and nature, is what makes the enterprise worthwhile.

From the outside looking in, the annual harvest is the most picturesque time of the vineyard year. Signs of nature about to deliver up its bounty are everywhere. The grapes have changed colour from green to red, the vine leaves turn reddish in sympathy and clusters of once embryonic petits pois dangle in pendulous bunches from the pregnant vine. As crunch time approaches, armies of villagers, students, backpackers and migrant workers descend on vineyards throughout Europe, marching up and down vineyard rows brandishing secateurs. Baskets soon brim with swollen bunches of juicy grapes, ready to be transported to the crusher. The village wine queen is photographed for the local paper, adding to the impression that harvesting is one long party and the pickers are having the time of their lives. Maybe they are, but it's back-breaking work.

The instant the bunch is severed from the vine is the most critical moment of the entire winemaking year. Once a good kick to the base of the vine was enough to tell the grower if the vine was ready. Today's buzzwords are precision viticulture, the hi-tech use of scientific data, from satellite images to yield monitoring and target sampling. After the grapes have been carefully nurtured by the grower, who's suffered sleepless nights warding off fungus, rot, pests and diseases, they are analysed and tasted and re-tasted for the best natural balance of fruit sugar, acidity and tannin – in a word: ripeness.

The moment of truth has arrived. As the grape is secateured from the vine, it's taken towards the winery hopper where it's de-stemmed to be pressed if it's destined for white wine, or crushed if it's red. In a modern set-up, bunches are taken in small plastic crates direct to the sorting conveyor belt. Sorting is the new mantra of the vendangeur. Workers are trained to reject unripe, raisined, split or rotting grapes and retain the good ones. Coupled with improved techniques in the vineyard, this makes a difference, especially in years like 2007.

Considering all that effort made by the vine, and those who nurtured it during the year, it's astonishing how dependent it still is on the weather during the harvest itself. Today's growers rightly pride themselves on progress in the vineyard and scientific advance. Some will even go so far as to say there's no such thing as a bad harvest any more, just one that's less good than it might have been. But there's still denial and wishful thinking about, especially in the face of climate change. However much the inconsistencies have been ironed out by science, vintage variation is a fact of life.

The news on the grapevine is that 2007 in France is going to be patchy. In Bordeaux, summer was cool with high rainfall and problems of mildew and rot. At the beginning of the month, cool, fine weather was drying out the vineyards ready for the harvesting, which ends with cabernet sauvignon in early October. At worst, the vintage will be mediocre, at best salvation will make it respectable. Burgundy too suffered this year with a cool, wet summer, but a cold north wind from the start of the month blowing like a giant hair dryer has eased fears. No one's talking "good" or "great" but rather "not-as-bad-as-it-might-have been". The words "vintage of the century", for once, have not been, nor will be, uttered.