The Met Office has issued a yellow warning for dense fog across much of England and eastern Wales, running from 18:00 on Sunday until 11:00 on Monday.
The warning covers an area of the southern UK stretching from Canterbury to Cardiff, Hull to St Asaph and Southampton to York, and includes London, Birmingham and parts of Greater Manchester.
Visibility could fall to less than 50m in places, making driving difficult. Bus, train, ferry and flight services could also face delays or cancellations.