The National Weather Service issued a dense fog advisory on Thursday at 5:15 a.m., valid until 9 a.m. This advisory covers the Higher Elevations of Indiana and also includes Mercer, Venango, Forest, Lawrence, Butler, Clarion, Jefferson, Armstrong, and Indiana counties.
The weather service warned that “Visibility one quarter mile or less in dense fog” should be anticipated.
“Hazardous driving conditions are possible due to low visibility,” the weather service noted, advising drivers to “slow down, use headlights, and maintain ample following distance.”

Navigating Fog: Weather Service Safety Guidelines for Drivers
An issued dense fog advisory signals the presence of widespread dense fog, significantly reducing visibility to a quarter-mile or less. Such conditions create difficult travel circumstances, necessitating extreme caution on the road, or ideally, rescheduling your journey.
Should you need to drive through fog, remember these essential safety recommendations from the weather service:
Lower your speed:
Drive more slowly and allow additional travel time to ensure a safe arrival at your destination.
Maximize visibility:
Make certain your vehicle is easily seen by others; turn on your low-beam headlights, as these will also activate your taillights. If available, engage your fog lights.
Do not use high-beams:
Avoid using high-beam headlights, as they can cause excessive glare, which will worsen your ability to see the road ahead.
Keep ample distance:
Ensure a substantial following distance to allow for sudden braking or changes in traffic flow.
Remain in your lane:
Use the road’s lane markings as a reference to help you stay properly aligned within your lane.
When visibility is minimal:
If dense fog reduces visibility to near zero, turn on your hazard lights and locate a secure area, such as a business parking lot, to safely pull off the road and stop.
If no safe parking is available:
Should a designated parking spot be unavailable, guide your vehicle as far from the roadway as you can. After stopping, switch off all lights except for your hazard flashers, apply the emergency brake, and lift your foot from the brake pedal. This ensures your tail lights are off, reducing the risk of another vehicle hitting your stopped car.
Following these guidelines from the weather service will help you navigate foggy conditions with greater safety, minimizing accident risks and safeguarding your well-being.