The Met Office is warning that freezing fog may linger across the region until late morning in some places.
It says fog will be a hazard on roads, and that ice will also be a problem for drivers and pedestrians.
It's issued a yellow warning covering the whole region.
The Met Office has issued a yellow warning for fog in the East of England.
Areas of freezing fog, some dense, are expected to form again during Monday night and into Tuesday morning.
The Met Office says the fog will become widespread in places and driving conditions will be difficult with journeys likely to take longer than usual.
It is possible there will be delays to air travel.
The weather warning covers the whole of the Anglia region and is valid from 5pm on Monday 23 January until 11am on Tuesday 24 January 2017
"The fog will form initially, and will probably be most widespread, across parts of the southwest of England, southeast Wales and the southwest Midlands.
"Fog will also form elsewhere but areas of cloud are leading to uncertainty in the timing and extent of the fog and will result in the fog waxing and waning through the night and during Tuesday morning.
"However it is likely that some dense fog patches will develop in other parts of the warning area by Tuesday morning.
"The fog is expected to slowly thin and lift during Tuesday although it may persist in some areas throughout the day."
The Anglia region is heading for its coldest January since 2013 following on from three relatively mild starts to the year.Read the full story ›
The Met Office has issued a fog warning for parts of the East of England.
Forecasters say Central Bedfordshire, Hertfordshire, Luton, Essex, Southend-on-Sea and Thurrock could all be affected.
The fog will begin to come in Sunday evening but is likely to cause most problems overnight and into Monday morning.
The warning is valid until 10.30am on Monday 23 January 2017.
"Areas of dense and freezing fog may lead to journeys taking longer than usual, with possible delays to air travel.
"Watch out, too, for slippery surfaces."
The sun put on quite a display last night and our viewers captured some beautiful shots. Here are a few you shared with us...Read the full story ›
It has been a chilly night in the Anglia region with temperatures plunging below -6°C at Writtle in Essex.Read the full story ›
Cold arctic air will make it feel raw later in the week with the risk of sleet and snow in places.Read the full story ›
England has seen its coldest night of the winter so far and temperatures in the Anglia region dip to nearly -5°C.Read the full story ›
The Met Office is warning of icy conditions across parts of the Anglia region this morning. The warning is in force until 10am.
Drivers are being advised to take extra care on the roads following a yellow warning of ice.
Icy patches are likely to form on roads as temperatures dipped below freezing last night. Patches of freezing fog are also expected.
"After a very cold night and as moister air comes in contact with cold surfaces later, the potential for a lot of frost to form, rendering some surfaces hazardous.
"Please be aware that untreated surfaces, such as pavements and some minor roads, are likely to turn very slippery on Tuesday morning."
A further Met Office yellow warning has been issued for thick fog across the Anglia region as weather conditions cause delays and cancellations at airports.
Stansted airport in Essex says that heavy fog is affecting flights to and from the airport leading to delays and cancellations. It is advising passengers to check with airlines and allow extra time for journeys to the airport.
Flights into and out of Luton airport are also affected by fog.
The airport says there have been a number of delays to arrivals and departures. Passengers are advised to check in as normal.
The Met Office weather warning is in force until 10am on Saturday 31 December.
"Areas of fog have persisted in places through Friday and are expected to become more widespread and freezing in places again on Friday night and into Saturday morning.
"Driving conditions will be difficult with journeys likely to take longer than usual and delays to air travel possible.
"Fog and freezing fog patches with visibility less than 100 metres in places are expected to become more widespread."