Weathermen said the misty conditions were likely to remain until 10am or later, with visibility down to 50m on some routes.
Flights from Southampton to Glasgow, Manchester, Guernsey and Belfast were delayed and the airport announced the 8.20am flight to Jersey and the 8.25am service to Leeds would not run.
A Met Office spokesman said: ‘Fog is expected both on hills and at low levels. Visibilities will be very variable, and as low as 50-100 m in places.
‘Whilst much of it will clear by 10am, some patches may linger for the rest of the morning.’