Clear skies and light winds at this time of year are a recipe for fog to develop. Overnight temperatures plummeted to -8C (not as cold as the -10C seen yesterday morning, but it is more widespread).
Through recent days we have dragged moisture from the North Sea and near continent and it is this that has condensed overnight giving such widespread and dense fog.
The fog is widespread, affecting visibility across much of England from north to south, east to west and also east Wales. It had been as low as 100m at RAF Brize Norton where troops and cargo are heading to and from Afghanistan.
Heathrow, Stansted and many other airports have seen visibly down to between 150-300m.
This has led to delayed and cancelled flights.
Allow extra time to defrost your car and for your journey today, check before you travel and take care as it could also be icy.
The fog will be slow to clear through the morning and for some will linger all day.
The vale of York, Lincolnshire and East Anglia could be worst hit and here the temperature will struggle to even recover to freezing.