Drivers in France warned of ‘summer black ice’ risk this weekend

Drivers in France are being warned of the risk of ‘summer black ice’ on the roads this weekend as heavy rain is expected following an extended warm spell. 

The phenomena – known as verglas d’été in French – can appear after a prolonged absence of rain is suddenly interrupted by a downpour. 

The unexpected slipperiness of roads – it can feel similar to driving on icy roads – can cause drivers to lose control of their vehicles, leading to accidents.

What is ‘summer black ice’?

Despite its name, there is no ice involved. 

“It's an ice-like phenomenon that occurs during the first rains that fall on dry ground after a long period of drought like we've experienced,” said meteorologist Guillaume Séchet to French media outlet Actu.fr. 

The ‘black ice’ in question is actually a thin film of vehicle pollutants that covers the surface of roads. 

When rain falls on dried-out roads, this layer can become slippery. 

“Air pollutants (especially fine particles) accumulate on the asphalt, and with the rain create a pollutant/water mixture, which can… make roads slippery in the most polluted areas,” Mr Séchet added. 

This can apply both in cities and to busy motorways and major national roads, which see thousands of vehicles pass and accumulate significant pollution. 

Although vehicle pollutants are the main particles, tyre fragments, oil, fumes, petrol and dust can all accumulate to create the so-called ‘black ice’. 

Rainy weekend ahead increases likelihood

The phenomenon is most common in summer (hence the name) however is not linked to temperatures and can occur whenever there has been a long dry spell. 

Some areas in northern France have not seen any rain for a month – rare for a spring – however the entirety of the country is set to experience heavy rain this weekend and the start of next week. 

The likely presence of ‘summer black ice’ will peak on Sunday (April 13) – after this, extended rainfall will wash away this initial slippery mixture. 

State forecaster Météo France issues warnings for drivers in the case of traditional black ie (verglas), however not for its summer equivalent. 

Drivers will therefore need to take their own precautions, alongside those generally in place during rain.

Read more: Do adverse weather conditions affect driving rules in France?

Keeping your distance from the car in front of you, and slowing down at sharp bends/difficult sections of the road is recommended.

If you do skid, the following advice is given by French gendarmes.

“If the rear of the car slides out, countersteer, gently release the accelerator, brake gradually, and declutch. If the front of the car slides out, it is important not to steer because the car must return to a straight trajectory. In this case, release the accelerator and brake hard.