“The conditions created ideal ripening for all grape varieties throughout Bordeaux thanks to an exceptionally dry August and September, without excessive heat” 

Bordeaux has been considered a marginal climate for growing grapes. To produce outstanding vintages, like 2005, 2009 and now most probably 2010, there are five elements needed. 

There are five conditions that "make" a perfect vintage for Bordeaux.

Left & Right Bank Red Wines

2010 fits all the above conditions thanks to a remarkably dry summer (but without any heat waves) that continued into a sunny, medium-warm autumn with average precipitation. The vines underwent greater and more widespread water stress in 2010 than in 2009. In that respect, 2010 is more similar to 2005 than 2009. The only issue being Merlot, with a slightly cool and wet June causing issues during fruit set. This vintage, has produced highly alcoholic wines, but generally less than 2009.

This statement is not entirely true of the Right Bank where alcohol has crept up, with many wines above that of last year. The balance of 2010 makes it a classic Bordeaux vintage, with fantastic structure, tannin and acid. Some of these wines are monsters, that will need extended aging to show their best. However, unlike the '82 verus '83 vintage, 2010 has just as much hype as 2009.

Cabernet and Cabernet Franc are the standout varieties, with most picking later than 2009, but before the rainfall in early October. These two varieties have produced fragrant, aromatic wines with great structure, high tannin and acid.

Merlot has produced alcoholic wines, sometimes more than 2009, with most above 14% and some above 15%. This appears a little strange given the issues of fruit set during a wet June and many were harvested during the October rains. The power of these wines places them similar in style to those of 2009.

Sauternes & Barsac

The moderately warm daytime temperatures and cool nights in August and September encouraged the synthesis of aroma precursors and maintained good acidity in the grapes. This means that 2010 was also a very great vintage for white wines, as much for Sauvignon Blanc as for S é millon.

The development of noble rot at the right time, as soon as the grapes are ripe, determines whether a vintage will be great in Sauternes and Barsac. This calls for alternating periods of mist or fog (conducive to the spread of botrytis) and drier, warmer, or more windy periods to concentrate the grapes. Without being as tremendously concentrated as 2009, 2010 will undoubtedly be a great vintage for sweet white Bordeaux, and a fitting end to an outstanding decade with an uninterrupted run of good-to-excellent vintages, the like of which has never been seen in the region.

These wines don't have the opulence and lushness of 2005 and 2009, potentially making them the most floral, refined and delicate wines of all time. This vintage was almost perfect in terms dry periods and rain, meaning the grapes were concentrated without being over-ripe. This makes for potentially the best vintage of all time for the sweet wines of Bordeaux.

The Technical - Review of the Weather During Vintage

Marked by three cold waves in mid-December, early January, and mid-February, the winter of 2010 was as grey, long, and harsh as 2009. Subsequent to a cold winter and a month of March close to the seasonal average it was impossible for bud break to happen early. This occurred from early to mid-April, just a few days later than 2009 and 2008. However, the vines made up for this slight delay thanks to a sunny, warm, and remarkably dry month of April.

May was also fairly dry, but slightly cooler and more overcast than in 2009. Cold weather returned in early May and it was necessary to wait until the 18 th for an anticyclone to produce a warm, dry airstream. The temperature rose from then until the 26 th , becoming very high for the season, and even going above 30 ° C on the 24 th of May. However, the thermometer dropped once again starting on the 26 th   and the weather turned cool and dismal for several days. This meant that May 2010 was the coolest month of May of the decade: 0.7 ° C lower than average and accompanied by a decided lack of rainfall – just 41 mm compared to the average of 83 mm.

The first vines started flowering in late May, and mid-flowering in Merlot and Cabernet occurred between the 4 th and the 9 th of June in our reference vineyards, several days later than in 2009. However, for 14 days, from the 6 th to the 19 th of June, the weather was turbulent and occasionally very cool. Storms broke out with strong cumulative rainfall. Such conditions were not conducive to pollination. Whereas most white and red wine varieties experienced satisfactory fruit set, Merlot grapes were affected by coulure (shot berries) and millerandage ("hens and chickens"). As usual, old Merlot vines, often affected by viral diseases, suffered the heaviest crop losses. The perturbed flowering of Merlot is the only shortcoming of the 2010 vintage.

By late June, cumulative temperatures above 10°C from January amounted to an average of 573.6 degree days in the Gironde department, which was less than recent vintages, including 2004. However, the high temperatures in early July reversed this tendency and, by mid-July, the base 10 cumulative total was 721.5 degree days, which puts the 2010 vintage close to 2008 (722.8 degree days) and 2009 (743.7 degree days). The vines were thus able to make up partly for the delay in flowering.

As a contrast, July 2010 was hot, mainly due to especially high minimum temperatures at the beginning of the month. With a monthly regional temperature 1.3 ° C above average, 2010 arrived in eighth place with regard to the past decade. This was nevertheless far from the record of +3.9 ° C set in 2006.

During July 2010, it was warmer than that same month in either 2009 or 2005, but without a heat wave. With the maximum temperature only going above 30 ° C on three or four days. July also had slightly above-average sunshine and, significantly was much drier than usual. Precipitation during this month (less than 20 mm) was only a third of that in July 2009, and even less than in July 2005. Water stress thus gradually set in starting in late July 2010. This brought a complete halt to vine growth between the onset of v é raison (onset of ripening) and mid- v é raison .

In 2009, because of greater rainfall in July, this condition sine qua non for quality in successful red wine vintages in Bordeaux was only satisfied on soils with the lowest water reserves (mainly gravel and certain clay soils) i.e. the finest terroirs in Bordeaux. The halt to vine growth at the appropriate time was much more widespread in 2010 than in 2009.

Mid-véraison (colour change) occurred about the 6th of August for Merlot and around the 11th of that same month for Cabernet Sauvignon, i.e. 3-4 days later than in 2005 and 2009, and 4 days early than in 2008 or 2004.

The weather in early August was relatively cool and cloudy. However, starting on the 19th of that month, summer weather returned. This lasted until the harvest and led to optimum ripening for all grape varieties throughout Bordeaux.

In 2009, only the Médoc was spared by August storms, and the Libourne region experienced significant rainfall around the 20th of September. August, and to an even greater extent, September 2010 were very dry in all Bordeaux appellations. Precipitation in August was less than a third of the previous ten year average and the September figure was barely a quarter of the average for that month. With just 50 mm of precipitation from July to September, the 2010 vintage was the driest of the decade, even more than 2005, which had almost twice as much rain over the same period.

Despite this, evapotranspiration was average and did not cause a dramatic stop to water circulation. In certain instances, water stress was relatively strong, leading to fears of suspended ripening but, in the total absence of a heat wave, this was limited to certain young vines on soils that were very permeable terroirs on the Left Bank.

The vines resisted the drought conditions astonishingly well, especially in vineyards with ploughed soil. Starting on the 28th of August, although the weather remained very sunny, temperatures suddenly dropped below the seasonal average. Night-time temperatures were particularly cool, which was extremely beneficial to the accumulation of anthocyanins in red wine grapes and the retaining of aromas in white wine grapes. Less warm than in 2009, September 2010 had maximum temperatures comparable to 2005, but markedly cooler night-time temperatures.

Sunshine in August 2010 was close to the seasonal average. On the other hand, September and October 2009 were much more sunny than usual.

The weather was once again hot and dry in early September. The temperature went up from the 1st to the 5th, coming close to 30°C. The atmospheric pressure dropped on the 6th and storms swept the region from west to east on the 7th, bringing moderate cumulative rainfall that enabled the vines to finish ripening without suffering from the dry conditions. The weather turned calm, mild, and sunny from the 11th to the 20th of September, with cool nights conducive to very deep colour in the skins. This was especially ideal for Merlot.

In late September, autumn weather set in, with sunny days and cool nights, but without precipitation. These idyllic conditions lasted until mid-October, enabling Cabernet Sauvignon to ripen fully and obtain very promising levels of extractable anthocyanins. This is the key the great potential of the 2010 vintage.

In Summary

In a nutshell, summer and early autumn 2010 were drier and less warm (except for July) than either 2009 or 2005. The limited rainfall from July to mid-October was certainly the key factor in the success of the red wines in 2010 because, in an oceanic climate with wet winters like in Bordeaux, every dry summer produces very great vintages – with no exceptions to this rule. The reverse, however, is not necessarily true. Good wines are sometimes made in years with average rainfall in the months of August and September provided that July was warm enough to put a stop to vine growth at véraison, as was the case in 2008. The relatively cool, sunny weather that prevailed in 2010 during ripening was propitious to preserving good fruit and acidity. This was decisive for both the quality of white wines and the style of red wines.

 An edited version of The 2010 Vintage in Bordeaux: another very great year for both red and white wines.

Laurence GENY, Bernard DONECHE, and Denis DUBOURDIEU: Faculty of Oenology, Bordeaux Segalen University. Bordeaux Institute of Vineyard and Wine Sciences