California, specifically its Central Valley, has a unique weather phenomenon, the Tule fog. Throughout the fall and winter months, Tule fog dominates much of the Central Valley, at least during night and dawn. It is endemic to the Central Valley because of the mountain ranges that surround us. Tule fog forms when the ground cools rapidly (at night), affecting the air above it to reach dew point.

The heat of sunlight would dissipate it, but the Tulefog is capable of persisting for weeks or even months if strong turbulent winds aren’t present to break it up.

Tule fog can cover a distance of over 400 miles, stretching from Red Bluff down to Bakersfield. Even though it may originate in the Central Valley, it can drift westward towards the coast, all the way to the San Francisco Bay Area. As beautiful as it can be, it is also very deadly. Its visibility is at least 1/8th of a mile; more so, its visibility can vary drastically in a short amount of distance, changing from a somewhat comfortable eighth of a mile to zero visibility.

Doesn’t help that this fog suddenly descends on nights either, and in the cold months too, as if icy roads aren’t a danger enough. Remember to drive super safe; or not drive at all. If traversing other than from a car, better have lights to be seen, and reflectors.