The warning says the patches are set to ‘become more widespread and locally dense’ during Wednesday evening, overnight and through Thursday morning.
A Comment from the chief forecaster says: “A few patches of fog will persist during Wednesday afternoon across East Wales, the Midlands and eastern England, then reforming or thickening up over these areas quickly during the evening and more widely across the rest of the warning area overnight and into Thursday morning.
“Whilst not all areas will have fog, where it does form the visibility could be less than 100 metres.
“Combined with temperatures below freezing, there is also the risk of ice forming on some untreated surfaces particularly later in the night and early on Thursday morning.”
The Met Office adds that driving conditions ‘will be difficult with journeys likely to take longer than usual whilst some delays to air travel are possible’.