Weather: we explain why there is persistent fog over the Indre and Cher

Barely 11 hours of sunshine in Bourges since October 25. It's a very meager result according to the readings shared by Météo France and it's not even the fault of the rain. The Cher and the Indre are in fact under a layer of fog. “We have a lot of humidity near the ground. And with the anticyclone above us, there is a lot of mild air at altitude which pushes the cold air to the ground”explains Florentin Cayrouse, forecaster and vice-president of the Météo-Centre association. “We've had these fogs for ten or even fifteen days in places. We call it a blocking phenomenon and we can't see the end of the tunnel because this anticyclone is likely to stay for a long time in November”he adds.

In Bourges, we have just experienced the third least sunny October of the 21st century. In Châteauroux, data is not available. But since the beginning of November, there have only been three short hours of sunshine.

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With the fog, you have to adapt your driving

Driving in fog requires adaptation. “Very often, it is said that fog causes deaths. But it is the behavior of motorists that causes these tragedies”insists Nicolas Bornibus, road safety specialist and organizer of courses to recover points on the license. In Indre and Cher, there are no more accidents due to fog but the consequences are more serious. The risk of death and injury is twice as high as in an accident in bad weather. “A visibility of 50 meters implies a maximum speed of 50km/h. And fog that cools is called black ice so you also have to pay attention to grip”continues Nicolas Bornibus.

Reducing your speed is one thing. But you also need to be seen and see other road users. The dipped headlights must be supplemented by the fog lights at the front and rear. “There is a big lack of awareness. There are not enough people who check if their bulbs are working. We very often come across one-eyed cars where a headlight bulb does not work”regrets Nicolas Bornibus.

Fog…but no rain

The good thing about this current fog is that it hardly rains. “We are very happy to find these anticyclonic conditions because it allows several areas to breathe after the heavy rains and floods”underlines Florentin Cayrouse. 850 millimeters of rain fell in 2024 in Indre – with the wettest month of October in the 21st century. However, fog is not all good. “The humidity still remains very present and the soils are not drying out as much as we could have hoped”he adds.

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