Exceptionally mild weather across the vineyards of France this winter

ould winter mildness end up causing pain for farmers? “The Azores high pressure system is letting the southern currents through. December's temperatures are 2°C above average”, says Emmanuel Buisson, weather expert at Weenat. “The unseasonal weather patterns will last at least until mid-January. Plants will have experienced an imitation spring for almost a month”, adds agro-climatologist Serge Zaka (ITK).

As a result of the unseasonal weather, budburst could occur much earlier in vineyards in Bordeaux, the South-West, Pyrénées-Atlantiques and Orientales, and across the entire Mediterranean rim.

The cold start to the winter has released endodormancy in many wine regions. At the Agro Institute in Montpellier, viticulture professor Alain Deloire has done the maths for the area. “The weather station at the Montpellier Agro Institute indicates 11 days at 8°C or less since November 1st. The vines have therefore entered into ecodormancy”.

According to the literature, it then takes about 10 days at more than 10°C for the budburst process to begin. “Depending on the model, we're talking about 9°C for Merlot and 12°C for Cabernet Sauvignon”, explains Loic Debiolles, viticulture manager at ITK. With climate change, Alain Deloire places the cursor at 15°C, with equivalent temperatures in the soil to allow the roots to pump water.

For the agro-climatologists, February is when it all comes together. “The month was initially forecast to be cold and dry, but the trends are less and less clear”, deplores Emmanuel Buisson.

Winegrowers themselves don’t seem too concerned. “In Bordeaux, the pruning season is well underway. It will be mild for a few more days and then the weather should get colder”, says Joël Ortiz, director of the South Gironde department of the chamber of agriculture.

Let's hope so, because, “without cold weather to ‘press the reset button’ on vines”, experts predict that budburst could start on the first vines around mid-February, starting in the Perpignan area. And seasonal forecasts are predicting an anticyclone situation in April, which means frost.