Bordeaux Wine Guide: Climate
Bordeaux lies on the 45th parallel and has a very temperate climate, partly due to its latitude but also due to the moderating influence of the Atlantic Ocean and Gulf Stream, the latter bringing warmer waters from further south. This warming effect reaches far inland thanks to the presence of the Gironde Estuary, the size and influence of which is not to be underestimated. As the water courses past the vineyards of the famous Haut-Médoc communes of Margaux, St Julien, Pauillac and St Estèphe the estuary is many miles wide, reaching seven miles at its greatest. It is an obvious location for the siting of a nuclear reactor or two, a huge supply of cool water being essential for the operation of such reactors. Take a view across the Gironde from the vineyards of St Estèphe or St Seurin de Cadourne and it is difficult to overlook the twin reactors of the Centrale Nucléaire du Blayais on the opposite bank.
Nevertheless, despite the moderating influence of these huge bodies of water, Bordeaux is not immune to extremes of weather, some of which can be very damaging to the vines, and some of which can profoundly affect the quantity, quality and style of the wines ultimately produced. Winter and spring frosts are the biggest dangers to the vine, followed by hail which, strangely, seems to wreak its devastation at the least expected moment; July or August hailstorms are not that unusual.
Winter and Spring
As a consequence of its favourable latitude, perhaps helped by the phalanx of water penetrating deep within the region, winter in Bordeaux is generally mild, rarely generating the sort of temperatures that are severe enough to permanently damage the vines. But this has not always been so. The 1956 vintage is the case in point; a severe winter frost killed many vines and as a consequence there was a widespread need for replanting in the years that followed. With a changing climate bringing every milder although more erratic weather, the recurrence of such an event in modern times seems unlikely, although not impossible.
Although spring is usually mild frost at this time can also cause severe problems, damaging the tender new buds, shoots and leaves (pictured above, in Lalande de Pomerol, April 2012). Again, this is now becoming something of a historical issue it seems (although that does not stop the Bordelais worrying about it). The most recent spring frost to do any great damage was in April 1991. The thermometers bottomed out well below freezing, at around -7ºC, on Sunday April 21st. It was described by Christian Moueix as a disaster; the fact that many still remember the exact date, more than twenty years on, gives some indication of just how much of a disaster it was. In these days of ever-rising global temperatures, when almost every other vintage coming out of Bordeaux is a ‘Vintage of the Century’, it seems difficult to even conceive of such a catastrophic event, but in some areas the frost wiped out 80-100% of the crop, according to Moueix. And because the replacement buds had a late start, what was harvested was picked late, under an autumnal deluge. The wines were, in many cases, the worst to come out of Bordeaux in recent decades.