Chateau Guiraud

The microclimate

The micro climate

Additional information


Botrytis cinerea

Microscopic fungus that grows on many fruit types among which grapes.


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The climate of Sauternes appellation is oceanic like. Winters are pleasant and wet (5/10)°C), spring, also wet, is warm, helping the growing of the vines. Summers are not too hot (from 20 to 30°C), which helps a progressive ripeness.

It is during autumn that the climate is a bit different from a normal oceanic weather; helping the developing of a microscopic fungus called Botrytis cinerea* or noble rot. The region of Sauternes is under a special micro climate which explains the unique character of its wines. During morning, mists cover the vineyards. The moisture helps the botrytis work.

The sun appears during the morning, so that mists vanish and hot temperatures dry and concentrate the grapes. The wind also has a key role, helping to save or loose a harvest. A dry north east wind will dry up the vineyards, and help the concentration in the grapes. A west wind will announce rain and possibly the lost of part of the harvest.

The annual rainfall is about 860mm. Most of which falls in winter in a direct relation to Atlantic storms. Summer rainfall averages 50-60mm per month.

Sunshine and high temperatures reaching 30°C in July and August speed up the grapes maturity. But it is September and October sunshine and rainfall which decide of the vintage quality.