Freezing Fog: The Danger & How to Avoid It

Freezing Fog: The Danger & How to Avoid It
Posted in: Weather 101
By Steve LaNore, Certified Broadcast Meteorologist
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Freezing Fog: The Danger & How to Avoid It

Nature has a big arsenal of cold-weather trouble to aim our way, and sometimes that comes in the form of freezing fog. This stealthy winter villain causes dangerous travel conditions and it is often very tough to spot — but there are some simple ways to keep you out of its icy clutches.

In this article we break down what freezing fog is, how to spot it and what you should keep in mind should it be on the forecast.

What is Freezing Fog?

Regular fog is made up of millions of microscopic water droplets floating around in air that is above freezing. Literally, fog is a cloud on the ground. “Freezing fog” is a cloud of super-cooled water droplets; they turn from liquid to solid the minute they come in contact with a bridge, mailbox, truck windshield, stairs or even a road. The coating is fine— less than one millimeter thick in most cases—so you just can’t see the ice.

Conditions Favorable for Freezing Fog

Freezing fog can form in a humid atmosphere with temperatures between 14 and 32 degrees. The wind is usually light; skies can be clear or cloudy depending on the overall weather pattern of the day. Freezing fog and freezing drizzle often occur together, which creates a more dangerous situation than freezing fog by itself, because there’s a little more ice involved. Either way, freezing fog is bad news since it’s a hidden hazard.

Freezing Fog vs Ice Fog

While freezing fog is composed of very cold tiny liquid droplets floating in the air, ice fog is made up of tiny ice crystals suspended in the air. Ice fog occurs in colder climates where the temperature is below 14 degrees. It doesn’t stick to exposed objects since it’s already frozen, and it’s less dangerous to pedestrians and motorists.

freezing fog how to stay safe

How to Stay Safe in Freezing Fog

Freezing Fog Advisory

The National Weather Service often issues a “Freezing Fog Advisory” when conditions favorable for freezing fog develop. Pay attention to these weather statements and allow extra time to get where you are going or consider waiting until conditions improve. If an advisory is issued, consider waiting for conditions to improve before you leave the house. Sometimes, freezing fog will only take an hour or two to dissipate as temperatures warm up.

If You Must Travel

Driving in icy conditions is always a gamble. Freezing fog doesn’t always create enough ice to make the roads icy, but sometimes it will, and this can vary as the miles pass. Drive at or below the speed limit, avoid sudden lane changes or braking, and allow more time than usual to stop. Make sure the headlights are on and use your low beams to avoid blinding other drivers.

Winter Weather Wisdom from Your Own Backyard

Let’s face it, the more you know, the better your decisions will be—and that’s certainly true with winter driving.  Freezing fog can “sneak up” on you, and sometimes there won’t be an advisory posted, but there will still be danger on the roads. Installing an AcuRite weather station on your property can help you track the cold and moist conditions that can lead to freezing fog. Even if you’re not driving, you’ll want to know when slippery sidewalks are lurking out there.


Freezing fog brings high-level danger to winter driving because it cloaks an icy menace that’s exceedingly difficult to see. Monitor your AcuRite home weather station along with National Weather Service bulletins to stay on top of dangerous winter weather and conditions that can produce freezing fog. Avoid driving in these conditions whenever possible and remember to tread lightly on the sidewalks too!

Have you experienced freezing fog? Share your stories below!


September 17, 2020