If outdoors, consider seeking shelter inside a building.
Clearing skies, light winds, and lingering low-level moisture are
helping areas of valley fog to develop and become dense late
tonight. This fog will continue to expand through the night but
likely remain the densest in the valleys. Visibilities will be
below a quarter of a mile at times in the thickest of the fog. Be
sure to slow down and use your low beam headlights when you
encounter any fog.