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California DMV Study Guides

Driving in Rain, Fog & Bad Weather in California

California's diverse geography creates wildly varied driving conditions. From coastal fog to mountain snow to desert dust storms, drivers must know how to adjust their behavior when conditions deteriorate.

Driving in Rain

Turn on your headlights when it's raining — California law requires headlights when windshield wipers are in use. Increase your following distance to at least 4 seconds. Reduce speed below the posted limit if conditions are unsafe (Basic Speed Law). Watch for hydroplaning — ease off the accelerator and steer straight if your tires lose contact with the road.

Driving in Fog

Use your low-beam headlights in fog — high beams reflect off the moisture and reduce visibility further. Reduce speed significantly. If fog is extremely dense, pull completely off the road and turn off your lights so other drivers don't follow your taillights. Use fog lights if your vehicle is equipped with them.

Wind & Other Conditions

Strong crosswinds affect high-profile vehicles (trucks, SUVs) most severely. Grip the steering wheel firmly and be prepared for sudden gusts. In dust storms, pull off the road completely, turn off your lights, and wait for conditions to improve. On icy roads, accelerate and brake gently, and increase following distance to 8-10 seconds.

Key Rules at a Glance

  • Headlights in rain: Required — turn on when wipers are in use
  • Fog — headlight type: Low beams only; high beams reduce visibility
  • Hydroplaning — correct response: Ease off accelerator, steer straight
  • Following distance in rain: At least 4 seconds
  • Dust storm: Pull fully off road, turn off lights, wait

Continue Studying

  • California Driver's License & Permit Rules
  • California DMV Knowledge & Drive Test Guide
  • California Signals, Horns & Headlights Rules
  • California Road Signs Study Guide
  • Traffic Lights & Pedestrian Signals in California
  • California Lane Markings Explained