Do high temperatures affect driving rules in France?

Reader Question: I read your article about hot weather causing speed limits to drop in the south of France. Are there any other hot weather-related driving rules we need to be aware of in France? 

You are correct that speed limits were temporarily lowered last week in a number of areas, due in part to high temperatures. 

Heatwave-level temperatures were one of the contributing factors to an increase in pollutant particle levels in the south and east of France, which in turn led to speed limits being lowered and restrictions on high-polluting vehicles in a number of areas. 

Unlike during certain other weather conditions however, driving rules are not routinely altered during heatwave conditions. 

Whereas heavy rain, storms, and other conditions can see maximum speeds drop automatically – and headlights must be used differently in foggy weather – there are no such rules during high temperatures. 

Drive sensibly when temperatures are high

This does not mean vehicles should be driven in exactly the same way during periods of extreme heat, however.

Drivers are still expected to alter their driving in light of circumstances even without official changes, and this includes being more cautious and driving slower in very hot weather. 

This should especially be the case if the weather conditions directly affect a person’s field of vision or if road surfaces are impacted by the heat. 

For example, driving in 35C heat leads to reaction times on average 20% slower than when driving in 25C heat. 

More generally, drivers should prepare themselves and their vehicle if planning to drive in hot weather. 

French road safety authority Sécurité Routière provides several pieces of advice for drivers, both prior to departing and when driving during hot weather. 

This includes: 

• Avoiding setting off at rush hour or driving during the hottest part of the day (usually 12:00 and 16:00)

• Ensuring your car is ready for a trip to avoid a roadside breakdown in the heat (tyres are pumped up, oil does not need changing, coolant levels are topped up etc)

• Checking traffic warnings in advance to avoid being caught in traffic (a traditional way to do this is via the Bison Futé service).

• Remember your sunglasses and wear loose, light clothing such as cotton when driving to avoid getting too hot

• Bringing plenty of water with you and drinking regularly even when not thirsty. Avoid drinking alcohol if planning to drive even if you would usually remain under the limit.

• Use your vehicle’s air conditioning, or open the windows regularly to ventilate. Bring a cool air spray to stay fresh.

• If driving for a long period, take plenty of breaks to rest and stretch your legs. Spend these breaks in the shade and out of direct sunlight, to help cool down, and park in the shade if possible to help your vehicle cool down.

• Keep an eye on elderly and young passengers to ensure they are not getting too hot

If you feel unwell you should stop driving and call emergency services using 15 or 112.