The Met Office has issued a weather warning to drivers in Sheffield over a potentially dangerous amount of fog that will hit by Monday morning.
The fog, which will reduce visibility to less than 100m at times, will begin to form on Sunday night, becoming widespread and dense in places by Monday morning.
They say travel may be affected, with some minor disruption expected.
The warning, which was issued at 11.45am today, comes into effect at 9pm on Sunday November 1 and will end at midday on Monday November 2.
It is in place for Yorkshire and the Humber as well as Derbyshire.