Special Weather Statement issued December 17 at 6:52AM CST by NWS Austin/San Antonio TX

Patchy dense fog is developing now into portions of the I-35
corridor. Local visibilities are being reduced to 1/4 to 1/2 mile
across some spots. We’ll monitor for a possible extension of a
Dense Fog Advisory into the area. If driving, slow down, use your
low beam headlights in fog, and leave plenty of distance between
you and other vehicles. Visibilities are forecast to improve
around 9 AM.