Speed and weather conditions
This is how you adjust your speed when weather and road conditions make the road more dangerous than normal.
The Road Traffic Act requires that you always drive at appropriate speed according to the conditions. Weather conditions affect both visibility and road grip, and you must reduce speed accordingly.
How different weather types affect driving
| Weather type | Main risk | Recommended measure |
|---|---|---|
| Rain | Aquaplaning, reduced visibility | Reduce speed, increase distance |
| Snow | Slippery roads, poor visibility | Use winter tires, drive carefully |
| Ice and freezing rain | Extremely slippery | Strong speed reduction |
| Fog | Very limited visibility | Drive according to visibility, use fog lights |
| Strong wind | Crosswind, instability | Firm grip on the wheel, lower speed |
Braking distance on different surfaces
| Surface | Braking distance at 80 km/h |
|---|---|
| Dry asphalt | approx. 64 m |
| Wet asphalt | approx. 128 m (double) |
| Snow | approx. 190 m (triple) |
| Ice | approx. 320–640 m (five to ten times) |
See calculation of stopping distance for the formulas behind these numbers. Increase distance according to the three-second rule to four, five, or more seconds.
Aquaplaning
Aquaplaning occurs when the tires cannot channel away the water, and the car slides on a layer of water. The risk increases with:
- High speed over 80 km/h
- Worn tires with low tread depth
- Large amounts of water on the road
Read more about this in rain, aquaplaning, and wind .
Practical tips for bad weather
- Check the weather forecast before driving, especially on long trips .
- Use proper lighting. See night driving and visibility for rules about lights.
- Be prepared for conditions to change quickly, especially in tunnels and on bridges.
- Stay updated via variable signs showing current information.
- Remember that warning signs indicate particularly exposed stretches.
Further reading
Read next
More in Class B course
Accidents involving vulnerable road users
Special procedures and considerations for accidents involving pedestrians and cyclists.
Accidents, reporting and first aid
Checklist for safe handling of accidents and proper notification.
Adapted speed and hidden danger
What adjusted speed means in practice, and how you anticipate hazards you cannot see.
Age limits and practice driving
Everything about age limits for class B and what is required for private practice driving with a companion.