"2013 had too much rain, 2014 was too cold, 2015... ah, 2015 had great weather, but too early to know all of its impact on the wine!" If you listen to the winemakers, it would appear that there's never a year fully free from climatic troubles. And they can put at risk a complete year's work. For all the skill of a winemaker, not everything can be controlled, particularly the good or bad fortune that the weather can bring.

What weather factors influence the harvest?

Of course some climatic factors are well known and can be almost controlled depending on the region. For example in the northern vineyards the winemakers can remove some of the leaves from the vines during the summer to allow more sun to reach the grapes and so help them to mature more quickly. In the south, regulated irrigation can be authorised if there is drought, or the grapes may be harvested earlier if there are sustained high temperatures.

But, often the weather can be unpredictable, striking violently and quickly. A large hail storm can completely strip a vine bear of its leaves, buds or grapes depending on the time of year. The frost can kill the first buds. Heavy rain can change the quality of the grapes, or rain during the flowering period can severely reduce the potential yield volumes.

The winemaker has to deal with whatever Mother Nature throws up. Even if there aren't any extreme conditions, a relatively wet year or a relatively dry year can change when the harvest will take place, can impact the quality of the harvest, or can even change the organisation of how the grapes are picked.

The main pre-occupation in the minds of the winemakers over the coming weeks will be in fixing the date for the harvest. It's important to do so as early as possible from a logistical point of view to recruit the teams of harvesters, to order the necessary equipment, and to get the tools, machinery, and cellars ready for the new harvest.

Choosing when to harvest is a balancing act between waiting for the perfect level of maturity and mitigating the climatic risks of rain or hail storms that don't do much good to ripe grapes. Rain can bloat the grapes, diluting the sugar and aromatic concentration levels to the detriment to the wine's quality, and hail can simply destroy the grapes altogether.

At the end of summer the winemaker is constantly inspecting the vines, observing the maturity of the grapes, and looking to the sky or scouring the weather reports to try and avoid any trouble.

The weather can be fickle right up until the end, and even during the harvest. Harvesting during the rain can dilute a wine's structure, and make the grapes more difficult to sort. It can also allow rot to set in if the grapes don't dry quickly, which in turn can reduce the quantity.

Picking grapes in the rain also means that the harvesters work more slowly, and if the weather is very changeable, it makes planning and organising the teams that much more difficult and time consuming to ensure that they are picking the grapes in the right vineyard depending on the maturity levels and risk of rot. And when it's really hot, sometimes the teams have to start earlier, or harvest during the night to pick fresher grapes.

These are just some of the headaches that the winemakers face during harvest period! Fortunately, for most of the time, the harvest remains one of the highlights of the year, where the wineries are bursting with energy and conviviality. If you would like to find out for yourself what harvesting is like, join us for a Harvest Experience Day and adopt some vines in one of our partner wineries!

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