In winter, it’s not unusual to see morning fog in the New Orleans area. Fog usually lifts by mid-morning, but it can get dense, especially just before sunrise.
Here’s how fog in our southern region usually forms: south winds from the Gulf of Mexico drag warm, moist air inland over relatively cooler land and lakes. The warmer air arriving near the surface cools to the dew point temperature, which is the temperature at which water vapor condenses. Water vapor in the air changes to liquid water droplets and creates clouds on the ground … and that’s how we get fog.