Fog occurs naturally in the atmosphere, and several sciences explain its formation. In Florida, fog can form at any time of year if the right atmospheric conditions are present. However, it largely depends on cooling temperatures and moisture and occurs more frequently between late fall, winter, and early spring.
It's the season for Fog in Florida. Tonight, much of North Florida and the Panhandle could have the visibility obstructed at least until 9 a.m. Wednesday. Drive safely. pic.twitter.com/I93LGUGV3y
— Florida Public Radio Emergency Network (FPREN) (@FloridaStorms) December 16, 2025
Types of fog and their formation
Radiation fog occurs when the ground is colder than the environment. It generally happens at night when the ground cools due to heat loss from the sun. The air near the ground cools, and, with sufficient humidity, these droplets form and remain suspended in the atmosphere. The lack of wind and weather with clear skies allows nighttime temperatures to drop, which is essential.
Thermal inversion effects in winter:
A thermal inversion causes persistent fog. With high pressure present, the cold and humidity stay near the surface and, at night, create fog that can often persist until long after dawn. This is common in valleys or basins.
If you ever drive and notice fog banks over vegetation on the sides of the road, this is due to a smaller-scale thermal inversion. While on the road, there is no fog because the air is slightly warmer and less humid (due to traffic, which also helps the air mix). The grass retains colder (dense) air, and the humidity creates clouds, which remain near the surface, forming the fog. A slight high pressure is applied over this area, which prevents it from dispersing.
Advection fog forms when the environment is humid and a cold air mass or humid air arrives over a cold area. It is more common during the day and usually occurs near maritime regions.
The National Weather Service's local offices issue dense fog advisories when visibility is 1/4 mile or less over an area.
Orographic fog is formed when humid air rises to the side of a mountain, condenses when it reaches a certain level, and usually covers the summit. Cold air can also descend from a hill or mountain and condense valley humidity, producing orographic fog. This last type of formation is usually much more expensive.
BONUS! What is mist?
Mist is often confused with fog, but its composition distinguishes it. It is composed not only of water but also of other suspended particles. Mist occurs over the sea. So what reduces visibility on roads will never be mist,