Poor visibility conditions can make driving more challenging, and conditions named in driver-safety guidance include rain, fog, snow, sun glare, and night driving.¹ This guide gives practical safety tips for preparing your vehicle, adjusting your speed and spacing, and knowing when to stop driving in rain, fog, snow, glare, and darkness.⁷

Poor visibility conditions

When visibility drops, driving risks rise, and poor visibility conditions include rain, fog, snow, and sun glare.¹ Rain can reduce driver perception, and it can be especially debilitating at night.¹⁰ Fog can occur at any time, and visibility can deteriorate rapidly. Winter weather can make driving more dangerous, especially in rain, snow, and fog.⁸

A budget-friendly approach starts before the trip because a complete pre-trip inspection can identify simple problems before they become dangerous on the road.⁷ Check windshield wipers and blades, mirrors, lights, reflectors, defroster, tires, and brakes before beginning a trip.⁷ Clean windows, lights, and mirrors because dirty surfaces greatly reduce and distort visibility.⁷ Allow extra time for weather-related delays so you do not feel pressured to drive faster than conditions allow.⁷

Basic setup

Use headlights correctly because headlights help you see and help others see you.⁸ In Oregon, low-beam headlights are required whenever windshield wipers are on.⁸ Drivers must use headlights when they cannot see people or cars 1,000 feet ahead, including in rain and snow.⁵ Low beam headlights help reduce glare in foggy conditions.⁴

Turn off cruise control during adverse weather so you remain in control of the vehicle.⁷ Increase following distance to give yourself and surrounding drivers extra space to react safely.⁷ Signal well in advance and make sure other road users see you.⁷ Brake earlier and with less force than usual to help prevent sliding.⁷

Rain

Rain affects perception by making it harder to see through rainfall and by changing visibility through headlamps, windshields, the road, and road markings.¹⁰ A bit of rain, snow, or ice can make roads slippery, and wet leaves can also be slippery and dangerous.⁹ Roads can be extremely slippery during at least the first 20 minutes of rain after a dry spell because grease and oil can build up on road surfaces.⁷

Slow down when rain begins, leave extra space, and make inputs gently because slippery road surfaces reduce the margin for abrupt steering or braking.⁷ Worn tires increase the chance of hydroplaning, so tire condition matters before the rain starts.⁷ Never drive through deep or moving water if you cannot see the ground beneath it.⁷ Watch for stopped or parked vehicles on the side of the road, on the roadway, or under overpasses during heavy storms.⁷

Fog

Fog on highways can be extremely dangerous because it is often unexpected and visibility can deteriorate rapidly. The best advice for driving in fog is not to drive in it when you can avoid it. If fog develops, watch for foggy conditions and be ready to reduce speed. Do not assume fog will thin out after you enter it.

If continuing in fog is unavoidable, use low beams rather than creating extra glare.⁴ Fog reduces contrast, causing objects to become fainter and less distinct.¹⁰ Fog also affects perceptual judgments of speed and distance because of reduced contrast.¹⁰ Pulling off the road into a safe area is preferable when fog makes driving unsafe.

Snow

Snow, freezing rain, fog, and rain are named as unpredictable weather conditions that can make roads slippery and visibility difficult.⁹ Winter weather can make driving more dangerous, especially in rain, snow, and fog.⁸ Low-beam headlights at night during a snowstorm can help minimize snow glare.⁴ If windshield wipers are on, turning lights on helps other people see the vehicle.⁸

Use the same low-speed, high-space strategy in snow that you would use in other slippery weather.⁷ Brake earlier and with less force than normal to help prevent sliding.⁷ Increase following distance because extra space gives you and others more time to react safely.⁷ Avoid cruise control during snow or any adverse weather so you remain in direct control.⁷

Glare

Bright glare from the sun during peak periods is included among poor visibility conditions that can challenge drivers.¹ Low beam helps reduce glare in foggy conditions, and low beam headlights at night during a snowstorm can also help minimize snow.⁴ Clean windows, lights, and mirrors are important because dirty surfaces greatly reduce and distort visibility.⁷

For budget-friendly glare control, clean the windshield, mirrors, and lights before leaving rather than relying on costly accessories.⁷ If glare combines with wet roads, remember that rain interferes with perception through windshields, headlamps, road surfaces, and road markings.¹⁰ Keep speed low enough that you can respond to what you can actually see.

Night driving

Driving at night is riskier, with crashes happening about three times more often than during the day.⁸ Rain is especially debilitating at night because it reduces driver perception in several ways.¹⁰ Headlights make your vehicle more visible to others, and correct headlight use helps you see.⁸

Night driving in rain, fog, or snow calls for reduced speed, extra following distance, and smooth braking.⁷ Turn on headlights when visibility is limited by rain, snow, or other low-visibility conditions.⁵ Use low-beam headlights in fog because low beam helps reduce glare.⁴ If you cannot see enough roadway to continue safely, the best fog advice is not to drive.

Common mistakes

Avoid assuming fog will clear after you drive into it. Avoid cruise control during adverse weather because it reduces your direct control over the vehicle.⁷ Avoid following closely because extra space is needed for safe reaction time.⁷ Avoid dirty glass and lights because dirty surfaces greatly reduce and distort visibility.⁷

Avoid hard, late braking in slippery weather because earlier and gentler braking helps prevent sliding.⁷ Avoid driving through deep or moving water when the ground beneath it is not visible.⁷ Avoid starting a trip with worn tires because worn tires increase the chance of hydroplaning.⁷ Avoid treating light rain as harmless because a bit of rain can make roads slippery.⁹

Safety warnings

Do not drive in fog if you can avoid it, because the best advice for driving in fog is not to drive. Pull off the road into a safe area when fog makes continued driving unsafe. Never drive through deep or moving water if the ground beneath it cannot be seen.⁷ Watch for stopped or parked vehicles during heavy storms, including vehicles on the side of the road, on the roadway, or under overpasses.⁷

Give yourself more time before leaving because weather-related delays can require extra time.⁷ Make repairs or adjustments as necessary after checking wipers, mirrors, lights, reflectors, defroster, tires, and brakes.⁷ Use headlights correctly in rain, snow, fog, and darkness because headlights help you see and help others see you.⁸

Budget options

Start with low-cost maintenance: clean windows, lights, and mirrors before a trip.⁷ Inspect windshield wipers and blades before driving in rain or fog.⁷ Check mirrors, lights, reflectors, defroster, tires, and brakes as part of the pre-trip inspection.⁷ Plan extra time for delays so safety does not depend on rushing.⁷

Use driving technique as your cheapest safety upgrade: slow down, increase following distance, signal early, and brake earlier with less force.⁷ Turn on headlights in low-visibility conditions so others can see the vehicle.⁵ Use low beams in fog and during snowy night conditions to reduce glare or minimize snow glare.⁴

Checklist

• Inspect wipers, mirrors, lights, reflectors, defroster, tires, and brakes before the trip.⁷
• Clean windows, lights, and mirrors before driving.⁷
• Allow extra time for weather-related delays.⁷
• Turn off cruise control during adverse weather.⁷
• Increase following distance in rain, fog, snow, glare, or darkness.⁷
• Brake earlier and with less force on slippery roads.⁷
• Use headlights when visibility is limited by rain, snow, or low-visibility conditions.⁵
• Use low beams in fog to reduce glare.⁴
• Do not assume fog will thin after you enter it.
• Never drive through deep or moving water if you cannot see the ground beneath it.⁷

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