The Met Office has issued a yellow weather warning for fog across large parts of the United Kingdom, cautioning that travel could be disrupted as conditions align to produce what one of its meteorologists called a "perfect recipe" for dense fog.
The warning runs from 6pm on Sunday until 11am on Monday. It covers most of southern England, excluding the south-west, along with the entirety of the Midlands. Pockets of northern England and Wales are also included, with fog expected in cities such as Liverpool, Sheffield, York, Cardiff and Wrexham.
Niamh Murray, a Met Office operational meteorologist, said fog could still appear beyond the warning area, though in a less severe form. "There is still going to be patchy fog elsewhere, just not quite as dense or as impactful," she said, noting that parts of the West Country, Northern Ireland, much of the UK and even the central belt of Scotland could be affected.
Speaking to the Press Association, Murray explained that the season itself plays a central role. "With autumn and winter and getting fog during this time of year, we get much longer nights, and that allows temperatures to sort of fall away," she said. The extended cooling period and lower temperatures bring the air closer to the saturation point needed for fog to form.
She said recent conditions had combined to create ideal circumstances for widespread fog across England and Wales. "Another thing that we need to form fog is quite light winds, not absolutely no winds," she said. "We just have the perfect recipe at the moment: light winds, clear skies, long nights, to allow that fog to develop." She added that if temperatures drop below freezing, the fog "can be quite stubborn to clear the next day."
The Met Office said the fog is likely to be densest overnight on Monday in rural areas, including parts of the Midlands, Wales and East Anglia, where air frost is also possible.
Visibility in some areas may fall to as little as 50 metres or less, and the service warned that bus and train services could face delays. Flights in and out of the country may also be delayed or cancelled because of the heaviness of the fog.
Murray added that rain expected to follow the fog could bring some relief to drought-hit regions. "Across the south-west, where severe drought has been declared and is still enforced by the Environment Agency, there is a chance that we might see some very slow-moving rain, and you could see potentially accumulations up to 50 to 70mm," she said. The south-west is among the areas that have suffered droughts in recent months.
