Drivers in Northamptonshire are being warned that large areas of dense fog patches are expected to make visibility difficult on the roads on Monday morning.
The Met Office issued a warning of fog for Sunday morning and conditions are expected to be similar tomorrow.
Drivers are being advised to take extra care and expect some minor disruption to their journeys.
A chief forecaster for the Met Office said the fog on Sunday was due to a “slack, moist airmass lying across much of England and Wales”.
The forecaster said the fog reduced visibility to less than 100 metres at times.