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Topic 4 · Section 11

Weather Conditions

Adjusting your speed for weather is critical to maintaining control and avoiding crashes. Here’s how to handle various conditions:

🌧️ Rain

  • Roads become slick, especially just after rain begins (oil buildup on the road).
  • Reduce speed by 5–10+ mph under the limit to maintain traction and avoid hydroplaning.
  • Use windshield wipers and headlights. If you need the wipers because of rain, fog or snow, the low beams are required by law.
  • In a heavy rainstorm or snowstorm you may not see more than 100 feet ahead. If you cannot see farther than 100 feet, it is not safe to drive faster than 30 mph.

🌫️ Fog

  • Drive at a speed matching your visibility — if you can only see two lane stripes (each about 40 ft apart), that’s very limited.
  • 25–30 mph on a highway may be necessary in dense fog.
  • Avoid “bunching up” and don’t follow someone’s taillights blindly — if they veer off, you might too.
  • Use low-beam headlights — high beams reflect back and cause glare.
  • Never drive using only your parking lights or fog lights: fog lights go with the low beams, never instead of them.

❄️ Snow/Ice

  • Common in California mountain areas like the Sierra Nevada.
  • Slow way down and increase following distance to 8–10 seconds.
  • On ice, even low speeds are dangerous. Gentle inputs only: accelerate, brake, and steer slowly.
  • Chains may be legally required — carry them and know how to use them if driving in snow zones.

💨 High Winds

  • Gusty winds affect steering — especially for SUVs, vans, or trailers.
  • Slow down to maintain better control and be ready for sudden gusts (e.g., when exiting windbreaks or crossing bridges).
  • Look for warning signs in known high-wind areas.

🌅 Sun Glare

  • Blinding sunlight in early morning or late afternoon can obscure signals, signs, and pedestrians.
  • Use sun visors and polarized sunglasses.
  • Reduce speed to give yourself more reaction time when visibility is limited.
  • Be extra alert for traffic lights or hazards that may be hidden by glare.

In bad weather, the posted speed limit may be too fast.
Always slow down to a speed that lets you maintain traction and visibility.

Check you have it

179 practice questions cover defensive driving and safe driving practices, each explaining the reasoning behind its answer.

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Source: California Driver's Handbook (DL 600, rev. 6/2025). Edited by Fernando Aguilera. Aprobify is not affiliated with the California DMV.

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