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Fog Safety Tips for drivers, boaters and aviators

Aug 04, 2022 07:11AM ● By Editor
Photos: NOAA

From the National Weather Service • August 4, 2022

Fog, particularly when dense, can be hazardous to drivers, mariners and aviators. Fog contributes to numerous travel accidents every year. Restrictions in visibility resulting from fog can also impact takeoff and landing procedures and requirements for pilots, and can be the cause of weather-related aviation delays. This website offers information on the hazards of dense fog and how to stay safe. 

Dense Fog Advisory is issued by your local National Weather Service office when widespread dense fog develops. When this happens, visibilities frequently drop to one-quarter of a mile or less. These conditions make travel difficult. Take extra caution when on the road or avoid driving if possible.

Freezing Fog Advisory is issued by your local National Weather Service office when fog develops and surface temperatures are at or below freezing. The tiny liquid droplets in the fog can freeze instantly to any surface, including vehicles and road surfaces. Freezing fog makes driving, boating, flying and other forms of transportation particularly hazardous. Visibilities are typically at or below 1 mile.

Driving in Fog

If you must drive in foggy conditions, keep the following safety tips in mind:

  • Slow down and allow extra time to reach your destination.
  • Make your vehicle visible to others both ahead of you and behind you by using your low-beam headlights since this means your taillights will also be on. Use fog lights if you have them.
  • Never use your high-beam lights. Using high beam lights causes glare, making it more difficult for you to see what’s ahead of you on the road.
  • Leave plenty of distance between you and the vehicle in front of you to account for sudden stops or changes in the traffic pattern.
  • To ensure you are staying in the proper lane, follow the lines on the road with your eyes.
  • In extremely dense fog where visibility is near zero, the best course of action is to first turn on your hazard lights, then simply pull into a safe location such as a parking lot of a local business and stop.
  • If there is no parking lot or driveway to pull into, pull your vehicle off to the side of the road as far as possible. Once you come to a stop, turn off all lights except your hazard flashing lights, set the emergency brake, and take your foot off of the brake pedal to be sure the tail lights are not illuminated so that other drivers don't mistakenly run into you.
 Fog Over Water

Fog that forms over water is commonly referred to as sea fog or lake fog. It forms when warm, moist air flows over relatively colder waters. Sea or lake fog can occur over the Atlantic and Pacific Oceans, the Gulf of Mexico, the Great Lakes and other bodies of water. Fog is common along the U.S. Pacific coastline year round because the water is typically much colder than the nearby land. Sea fog is a type of advection fog, and therefore can move into land areas and result in hazards to motorists. Sometimes radiation fog that forms over land can move over bays, harbors, inlets, the intra-coastal and nearby ocean waters. While this is not pure sea fog, it can also be a concern for mariners. The National Weather Service issues Dense Fog Advisories when fog over water reduces visibility to 1 mile or less.

 Boating in Fog

Chances are when you are on the water you will occasionally encounter fog, making navigation a challenge. Because of the time it can take to stop or turn a marine vessel, fog is usually considered dense for mariners if it reduces visibility to less than 1 mile. Fog can form quickly and catch boaters off guard. Visibility can be reduced to a few feet, which can disorient even the most experienced boaters. The international standards for describing reduced visibility in marine forecasts are as follows:

  • Very Poor: Less than 0.5 nautical miles
  • Poor: 0.5 to less than 2 nautical miles
  • Moderate: 2 to 5 nautical miles
  • Good: Greater than 5 nautical miles

Learning to navigate through fog (or avoiding it) is critical to safe boating. These safety tips will help to keep you safe:

  • Slow down to avoid collisions.
  • Turn on all of your running lights, even in daytime.
  • Listen for sounds of other boats that may be near you or for fog horns and bells from nearby buoys.
  • VHF NOAA Weather Radio should broadcast important information concerning the formation, movement or dissipation of the fog. Pay close attention.
  • If your vessel has radar, use it to help locate dangers that may be around you.
  • Use GPS or a navigation chart to help obtain a fix on your location.
  • If you are unable to get your bearings, stay put until the fog lifts but make sure you are in a safe location.
  • Be familiar with horn and bell sounds you should produce to warn others around you when in dense fog.
  • Have a compass available. Even if you don't know where you are in the fog, with a compass you can determine the direction you are navigating.
  • Stay out of shipping lanes. Large ships cannot see you! Learn more about safe boating in fog

 Flying in Fog

Flying in fog is quite challenging, even for the most experienced of pilots. For pilots that are not as skilled, fog is an extremely dangerous and potentially deadly hazard. Each year, around 440 people are killed due to weather-related aviation accidents including the conditions of low visibilities and ceilings. If you are planning a flight and it’s foggy or will potentially be fog, follow these safety guidlines:

  • Get the latest forecasts, advisories and observations to help make your flight safe from NOAA's Aviation Weather Center.
  • Consider changing your plans to avoid flying in fog.
  • It is imperative that you specifically follow the Federal Aviation Administration mandated guidelines and flight rules for the specific flight category based on visibility and ceiling height. The ability to operate in fog depends on three factors: the capability of the pilot (i.e., instrument rating), the capability of the aircraft, and the capability of the airport. Flight categories are:
    • Instrument Flight Rules (IFR) or Instrument Meteorological Conditions (IMC): Ceilings below 1,000 feet AGL and/or visibility less than 3 miles.
    • Marginal Visual Flight Rules (MVFR): Ceilings, 1,000 to 3,000 feet AGL and/or visibility 3 to 5 miles.                        
    • Visual Flight Rules (VFR) or Meteorological Conditions (VMC), MVFR is considered VMC: Ceilings: greater than 3,000 feet AGL and visibility greater than 5 miles
  • If you must fly, it is important to know the layout of the airport you are departing from or arriving to, including the length and orientation of the runway, as well as the entire flying area.
  • Be aware of the potential for freezing fog. If temperatures are at or below freezing and fog is present, a thin layer of ice may form on the plane.
  • Always file a flight plan.

Take the free training courses offered by the COMET program, sponsored in part by NOAA. These classes can help you learn more about flying in fog and how other weather phenomena impacts aviation. 

For more information on safety with fog, follow these links.

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