Winemakers spend a lot of their time looking at the sky and pondering the weather.
Their crop is more sensitive than most to the sun and rain.
And the taste of wine depends almost wholly on the climate - so when that changes, the character of the wine changes, too.
Silvia Altare, a young winemaker in the Barolo-making region of northern Italy, says the weather is "90% of the work".
You also need to cross your fingers, he adds.
Not far from this week's UN climate change conference in Milan lies her family's vineyard at the foothills of the Alps.
Family tradition
Her father, Elio Altare, doesn't know how long his family has been growing grapes in this place. Hundreds of years perhaps.
He was responsible for his first vintage at the age of 16 and has helped put Barolo, made from the Nebbiolo grape, onto the global wine map.
He has used innovation and foresight to create a wine to his taste - which is demanding.
So this autumn he's not very happy with his vintage - though winegrowers would never admit to a bad year.
Lack of snow last winter, almost no rain in spring or summer and searing temperatures for prolonged periods have had a major impact on the grape harvest.
There has been a 20% reduction in output.
"Less water of course means less wine," he says.
Not only a smaller output (in an average year Elio Altare produces about 45,000 bottles from his 10 hectares, but, he says, some colour and flavour have also been lost.
The wine this year is "a little bit less great", he concedes.
Mr Altare will not admit to calamity.
Different character
The grapes they were picking this summer were, in some cases, like raisins. This means the flavour and sugar in the grapes are highly concentrated and they become unusually high in alcohol content - probably 16% instead of the usual 14%.
And the heat has spoilt the delicate flavour of his crop - and diminished his pleasure.
The talk this year among the younger generation of winemakers like his daughter Silvia and her friends has inevitably been about the climate.
They wonder whether the Barolo region will end up like Australia in a few years' time - producing heavier, "bigger" wines.
Mr Altare and his daughter have had to use resourcefulness and innovation in order to produce any decent wine this year.
They worked out ways to cool the overheated grapes down after picking and to cope with the unusually slow fermentation process caused by the high sugar concentration.
They have had to adapt their methods, are starting to discuss how they will deal with longer term climate changes, and are beginning to experiment with different varieties of grape.
Barolo's distinctiveness comes from the soil and the microclimate of the region, which sits in the shadow of the Alps. The Altare family say the Nebbiolo grape won't produce its special wine in other parts of the world.
If the long hot summer is part of a trend of global warming, the Altare Barolo wine might have a very different nature in the future.
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