The Met Office has issued a yellow warning for fog with slower journey times and delays to bus and train services expected.
Areas of fog are expected to continue to develop this morning becoming dense with visibility falling to below 100 m in places. This will lead to difficult driving conditions, slower journey times and some disruption. The fog will slowly clear after sunrise but may take until late morning to do so in a few locations.
The weather warning is in place until 11am on Wednesday.
Local areas affected in Wales