The first rain is the slickest
When rain starts after a dry spell, water mixes with oil and grime on the road surface and makes it especially slippery. Be extra gentle with the brakes and steering in the first part of a storm, until the rain has had a chance to wash the road.
Driving on wet roads
- Slow down. Tires grip less on wet pavement, so stopping distances grow. A safe speed in rain is often well below the posted limit.
- Double your gap. A common rule is to leave roughly twice your dry-road gap, about five or six seconds. See the gap ladder.
- Lights on. Use your low beams so others can see you. Many states require headlights whenever the wipers are running.
- Smooth inputs. Brake, steer and accelerate gently. Sudden movements are what break the tires loose.
- Skip cruise control. On wet roads you want direct control of the throttle.
Hydroplaning
When there's more water on the road than the tire tread can push away, the tire can ride up on a film of water and lose contact with the road. The car may feel light, the steering may go loose and the engine may rev. The risk grows with speed, standing water and worn tires.
If it happens, stay calm. Take your foot off the gas, hold the steering wheel straight or steer gently where you want to go, and avoid hard braking until the tires grip again. Good tread and correct tire pressure give you the best protection. See quick vehicle checks.
Never drive into flood water
Turn around. The National Weather Service warns that a few inches of moving water can push a car off course and that about a foot of moving water can float many cars. You can't tell how deep water is or whether the road under it has washed away. Find another route.
Driving in fog
Fog hides everything beyond a short distance and makes it hard to judge speed. Slow down until you can stop within the distance you can see. Use low beams and fog lights if your car has them. High beams reflect off the fog and make it harder to see.
- Use the right edge line as a guide, and open the window a little at intersections to listen for traffic you can't see.
- Leave a much larger gap than usual. Cars ahead may stop suddenly where the fog is thickest.
- Don't stop in a travel lane. If you can't see well enough to keep going, pull completely off the road at a safe spot, such as a parking lot or rest area.
- Rules about using hazard lights while moving differ by state, so check your state handbook.
Keeping your view clear
Replace wiper blades that streak, smear or chatter. Keep the washer fluid full. Use the defroster and air conditioning together to clear a fogged windshield quickly, since the air conditioning dries the air. Clean the inside of the glass regularly so it fogs less.
When to wait it out
Sometimes the safest choice is not to go. Heavy storms, flash flood warnings and dense fog advisories are good reasons to delay a trip. Check local weather alerts before you leave, and give yourself permission to stop somewhere safe if conditions get worse on the road.