Dense valley fog has developed overnight in typical areas but also into less frequently occurring locations, including in the southern Champlain Valley affecting Route 22A and US-4. The fog is more patchy across the higher terrain, but still present in many narrow higher terrain valleys. The fog will become more widespread around daybreak and reduce visibility to a half mile or less. Drivers are urged to use caution this morning and be prepared for rapidly changing visibility. Fog is expected to dissipate by around 9 AM.