Severe Weather: How Should You Behave While Driving?

Author: Michael Vogel

Oct 18, 2023 Safety on the road

Whether it’s a thunderstorm, heavy rain, hail, or flooding: How do you react if you get caught in severe weather with your car, motor home, or motorcycle? The basic rule is: Don’t take unnecessary risks.

Hailstones the size of golf balls. Masses of water that make a road impassable within seconds. Or gusts of wind that knock over trucks. In recent months, images like these have been in the news time and again. While some storms occur over a large area – like hurricanes – others are narrowly localized extreme events. Heavy rain can flood an entire town in a short period of time – but in the neighboring town it may only be spitting. But how do you behave as a road user in such a case? “If there is an official storm warning, the first mistake you can make is to set off at all,” says Markus Egelhaaf, accident researcher at DEKRA. “Hardly any journey can be important enough to expose yourself to that kind of risk.”
While driving: Full concentration, switch on low beam, and adjust speed
Having said that, anyone who is surprised by a storm while on the road should refrain from doing anything that poses additional risks. Egelhaaf recommends to “keep both hands on the wheel, don’t talk on the phone, use the radio only for traffic reports – no music, news, or the like.” This ensures that you pay maximum attention to the traffic, he says. During the day, don’t only switch on the daytime running lights but also the dipped headlights. You must also adjust your speed. “Overall, people often drive too fast and with far too little safety distance in these situations,” Egelhaaf criticizes.
When stopping due to weather conditions: Find a suitable spot
Anyone who would rather stop until the worst of the bad weather is over, should not do so abruptly. Especially not in the middle of the road. Better: Look for a suitable spot. “In the city, this can be a company parking lot in addition to regular parking spaces. On country roads, it’s perhaps the turnoff onto a dirt road,” says Egelhaaf. It is important that the vehicle does not become an obstacle for others.
“It’s especially difficult on highways. If there’s no exit, the only option is the emergency lane – but then only with the hazard lights and dipped headlights switched on.” In denser traffic, severe weather will cause a traffic jam on highways anyway. “On the other hand, simply stopping the vehicle beneath bridges is a dangerous habit, regardless of the type of road,” says the accident researcher. “The exception is, at most, motorcyclists who get themselves to safety on the far right edge of the road.”
Special hazards during storms: Caution is advised
During storms, forests and trees by the roadside are especially hazardous. Branches or entire trees could fall onto the road. On bridges, the wind hits vehicles unchecked from the side and with great force. Vehicles with a large surface area exposed to the wind are at risk, such as trucks, motor homes or caravans, SUVs, and vehicles with roof boxes. “In addition to bridges, exits from tunnels or when overtaking large vehicles can also be risky because the crosswind conditions change abruptly,” warns Egelhaaf. Motorcyclists are more at risk during squalls because, on two wheels, they are more susceptible to crosswinds. In addition, fluttering clothing, tank bags, or top cases are also unfavorably noticeable because they increase the surface area.
Heavy rain and hail: Avoid underpasses and depressions
In heavy rain or hail, try to avoid depressions and underpasses, where flooding can happen quickly. For example, water pushing up from sewer systems, drains clogged by leaves and mud, or streams that turn into raging torrents. “If a road is under water, driving through it is dangerous even if the water level is supposedly low, because you never know what the surface is like,” says the accident researcher.
Mud can reduce the grip of tires to the point where a vehicle will start to slide in low flow or even where there’s no flow. If manhole covers are washed out, open manholes hidden by the water can bring an abrupt end to a trip, even for vehicles with large wheels. Even if there are no such hazards, the overall height of the vehicle and the height at which the engine draws in air quickly set limits: The car might start to float or the engine might suck in water. If the vehicle is stuck in water, unable to maneuver, the occupants should get to safety as quickly as possible. “Depending on the situation, this will mean either getting to shore or onto the roof of the vehicle. In the second case, call 112 for help immediately,” says Egelhaaf.
The closed vehicle offers protection during thunderstorms
“A closed vehicle forms a Faraday cage,” says Egelhaaf. “If lightning strikes, the electrical energy is dissipated through the bodywork on the outside. The occupants are protected.” This is also true in modern convertibles with the roof closed, because the roll bar and the mechanics of the top are made of metal. In motor homes and caravans, on the other hand, protection is not necessarily provided if the outer shell is made exclusively of GRP (glass fiber reinforced polyester). In any case, no one is allowed to be inside a moving caravan.
Staying up to date
If you want to be up to date before you set off, you can find severe weather warnings in weather apps on your cell phone, for example. In Germany, the German Weather Service (DWD) is responsible for issueing alerts for weather-related hazards. There are a total of five alert categories. Category four (“official severe weather warning”) and five (“official warning of extreme severe weather”) are particularly critical. The Federal Office of Civil Protection and Disaster Assistance operates NINA, an app that also issues the DWD warnings from categories three and up. Of course, you can also keep up to date on possible severe weather by listening to the news on the radio or TV, but these are often not well differentiated geographically.