Marine Weather
Sea Fog Explained: Why Fog Rolls Over Cold Water
Why sea fog forms, where it is common, and how it affects beaches, boats, bridges, and coastal travel.
Quick answer: Sea fog often forms when warm moist air moves over colder water and cools until fog develops.
Water temperature contrast
Cold water cools the moist air from below.
If the air reaches saturation, fog can form and drift with the wind.
Why it surprises people
A sunny inland day can turn gray and cool near the coast.
Fog can move in quickly over beaches, harbors, bridges, and coastal roads.
Safety
Boaters should use navigation lights, sound signals, and reduced speed in poor visibility.
Drivers should use low beams and allow extra distance.