Why is Brittany burning so much?

It is an incredible situation that has occurred in recent days in Brittany: in the space of just one weekend, more than 30 fires have formed in Morbihan, as well as several others in Finistère, the Ille-et-Vilaine, and the Cotes-d’Armor. Although these outbreaks of fires are almost always of human origin, the conditions weather report of the last few months have led to very favorable conditions for fires. The risk of fire is currently at an extreme level over half of Brittany, and even at a “very extreme” maximum level over part of Morbihan, according to Copernicus data. Four meteorological parameters lead to this catastrophic situation in the region: the droughtthe heatsunshine and winds.

It has never been so hot in Brittany

Brittany is faced with a situation of drought sustainable for months: the rainfall deficit reached -40% from the 1^er January to August 7 according to Meteo France. An average of 308 mm of rain was recorded in the region, instead of a normal of 513 mm. This is the second driest year recorded in France, after that of 1976 (with only 196 mm and a deficit of -62%).

The level of heat, on the other hand, is completely new in Brittany : this is the hottest year recorded in the region since the start of weather records in 1947.anomaly temperatures reached +1.2°C above normal. Remember that in 1976, the Brittany region had not experienced any thermal anomaly, the temperatures were within the average.

A recurring dry wind in the region

Sunshine is also close to record levels since the beginning of the year, with a surplus of +25%. Another parameter aggravates an already high-risk situation, the wind. The presence of the anticyclone over northwestern Europe has been generating a recurring northeast wind for weeks, known to dry out vegetation. This dry wind was precisely present last weekend during the many fire starts and will also persist until Thursday or Friday, further increasing the risk of fire.

This combination of drought, historic heat, strong sunshine and dry winds led to an exceptional risk of fire. In this favorable context, the potential for fires to start is obviously multiplied in the middle of the tourist season: more human activity inevitably leads to a greater risk of fires. The few storms which should break out at the end of the week will perhaps be beneficial, but the dryness of the soil is such that a real lasting rainfall degradation would be necessary to hope for a real improvement.