Adverse weather conditions

Wet weather car

About Adverse weather conditions

Certain weather conditions can make driving extremely hazardous. To ensure you stay as safe as possible while on the road Somerset Road Safety has compiled a list of the more common forms of adverse weather, and detailed some helpful tips on how best to cope with driving in those conditions. Before setting out on a journey it is always a good idea to check the weather report so that your know what type of weather to expect along your route; to visit the Met Office web site click here.

Select from the list below to be directed to helpful advice on coping with driving in the chosen weather condition:

Flood water Fog Ice and snow High winds Hot weather Wet weather

Flood water

Driving through flood water is dangerous. If you are able to use an alternative route then do so; it’s far better to arrive late than not to arrive at all. Only drive through flood water if you are sure that it is shallow and, when making the decision on whether to drive through it or not, you should bear in mind the following facts:

30cm of flowing water is enough to move the average family car
60cm of standing water will float a car
15cm of fast flowing water can knock a pedestrian off their feet

Follow these tips when driving through flood water:

Check the weather report before you start your journey; if flooding is forecast then assess whether your journey is really necessary
If it’s raining heavily and visibility is reduced, make sure you use dipped headlights
Drive carefully and slowly. If you drive too fast it is all too easy to lose control of the vehicle by aquaplaning
In deeper water, driving too fast will create a bow wave which could force water into the vehicle’s engine – it only takes an egg-cupful of water to be sucked into a vehicle’s engine for it to be damaged
Use a low gear and keep the engine rev’s high; this will help to stop water from entering and damaging the car’s exhaust system
Do not attempt to drive through fast flowing water as your vehicle could easily be swept away
Water is generally shallowest in the centre of the road, so, if it is safe to do so, drive in the middle of the road
Always test your brakes after driving through a flooded section of road

Thick fog on road

Fog

Before entering fog check your mirrors then slow down. If the word ‘Fog’ is shown on a roadside signal but the road is clear, be prepared for a bank of fog or drifting patchy fog ahead. Even if it seems to be clearing, you can suddenly find yourself in thick fog.

When driving in fog you should

Use your lights as required
Keep a safe distance behind the vehicle in front. Rear lights can give a false sense of security
Be able to pull up well within the distance you can see clearly. This is particularly important on motorways and dual carriageways, as vehicles are travelling faster
Use your windscreen wipers and demisters
Beware of other drivers not using headlights
Not accelerate to get away from a vehicle which is too close behind you
Check your mirrors before you slow down. Then use your brakes so that your brake lights warn drivers behind you that you are slowing down
Stop in the correct position at a junction with limited visibility and listen for traffic. When you are sure it is safe to emerge, do so positively and do not hesitate in a position that puts you directly in the path of approaching vehicles.

You MUST NOT use front or rear fog lights unless visibility is seriously reduced. They dazzle other road users and can obscure your brake lights. You MUST switch them off when visibility improves.

Snowy weather

Ice and snow

In winter check the local weather forecast for warnings of icy or snowy weather. DO NOT drive in these conditions unless your journey is essential. If it is, take great care and allow more time for your journey. Take an emergency kit of de-icer and ice scraper, torch, warm clothing and boots, first aid kit, jump leads and a shovel, together with a warm drink and emergency food in case you get stuck or your vehicle breaks down.

Before you set off:

You MUST be able to see, so clear all snow and ice from all your windows
You MUST ensure that lights are clean and number plates are clearly visible and legible
Make sure the mirrors are clear and the windows are demisted thoroughly
Remove all snow from your vehicle that might fall off into the path of other road users
Check your planned route is clear of delays and that no further snowfalls or severe weather are predicted

When driving in icy or snowy weather:

Drive with care, even if the roads have been treated
Keep well back from the road user in front as stopping distances can be ten times greater than on dry roads
Take care when overtaking vehicles spreading salt or other de-icer, particularly if you are riding a motorcycle or cycle
Watch out for snowploughs which may throw out snow on either side. Do not overtake them unless the lane you intend to use has been cleared
Be prepared for the road conditions to change over relatively short distances
Listen to travel bulletins and take note of variable message signs that may provide information about weather, road and traffic conditions ahead.

Drive extremely carefully when the roads are icy. Avoid sudden actions as these could cause loss of control. You should:

Drive at a slow speed in as high a gear as possible; accelerate and brake very gently
Drive particularly slowly on bends where loss of control is more likely. Brake progressively on the straight before you reach a bend. Having slowed down, steer smoothly round the bend, avoiding sudden actions
Check your grip on the road surface when there is snow or ice by choosing a safe place to brake gently. If the steering feels unresponsive this may indicate ice and your vehicle losing its grip on the road. When travelling on ice, tyres make virtually no noise.

High winds

High-sided vehicles are most affected by windy weather, but strong gusts can also blow a car, cyclist, motorcyclist or horse rider off course. This can happen on open stretches of road exposed to strong crosswinds, or when passing bridges or gaps in hedges.

In very windy weather your vehicle may be affected by turbulence created by large vehicles. Motorcyclists are particularly affected, so keep well back from them when they are overtaking a high-sided vehicle.

Hot weather

Keep your vehicle well ventilated to avoid drowsiness. Be aware that the road surface may become soft or if it rains after a dry spell it may become slippery. These conditions could affect your steering and braking. If you are dazzled by bright sunlight, slow down and if necessary, stop.

Wet car, wet weather

Wet weather

In wet weather, stopping distances can be at least double those required for stopping on dry roads. The graphic below shows the typical stopping distance for a car on a dry road.

When driving in wet weather you should:

Keep well back from the vehicle in front. It is recommended that you leave at least a four second gap between your vehicle and the vehicle in front; this will increase your ability to see and plan ahead
If the steering becomes unresponsive it probably means that water is preventing the tyres from gripping the road. The best way to regain traction is to ease off the accelerator and slow down gradually
Remember that rain and spray from vehicles may make it difficult to see and for other drivers to see you
Be aware of the dangers of spilt diesel that will make the surface very slippery
Always take extra care around pedestrians, cyclists, motorcyclists and horse riders in wet weather as it will take far longer for your car to stop