A semi-continental climate
The Chablis wine region is at the northern end of Bourgogne, close to Champagne, and is very northerly for wine growing. The climat here is semi-continental, with long, harsh winters and hot summers. Far from maritime influences, the vineyards are sometimes hit by spring frosts. At the moment when the vine is coming back to life, sub-zero temperatures, even in springtime, can damage the buds as they prepare to burst, or the young shoots. Winemakers have learnt over time, and after significant losses in certain years, to mitigate these climatic hazards.
In 1959, the first "chaufferettes", or heaters, appeared in the vines. They give off heat but also create a cloud of smoke which limits radiation from the ground which cools it.
To counter frosts, another technique exists: aspersion. This consists of spraying water on the vines, which freezes on contact with the bud forming a protective cocoon around it: the frozen water remains at 0°C. The principle is the same as that for building igloos.
In certain years, spring frosts have been devastating for Chablis. Jean-Paul Droin, winemaker in Chablis, recalls: "1945 was a terrible year. My grandfather had bought his first electric press, but he didn't get to use it. All the vines were frozen on the night of 1 May. In 1957, only one hectoliter of Chablis Grand Cru was declared!"