The National Weather Service in Brownsville has issued a dense fog advisory for the entire Rio Grande Valley.
The advisory will remain in effect until 10 a.m. Friday.
The NWS reports visibility in some parts of the Valley could be a 1/4 of a mile or less because of the dense fog.
If driving, slow down, use your headlights, and leave plenty of distance ahead of you.
The NWS advises people operating boats to use proper fog signals and running lights.
