Areas of freezing fog, some dense, are expected to form again during Tuesday evening and last into Wednesday morning. The fog will become more widespread through the night, with icy patches on untreated roads and paths an additional hazard. Travelling conditions will be difficult with journeys likely to take longer than usual and delays to air travel are possible. Stagnant air will remain across the area, allowing fog to form readily. Frost deposited by the fog will give surfaces an icy covering which may be thick enough to make roads and pavements slippery. The weather warning covers Cambridgeshire, Central Bedfordshire, Hertfordshire, Luton, Norfolk, Peterborough, Essex, Leicestershire, Northamptonshire and Suffolk,