The Queensferry Crossing and Forth Road Bridge are among the worst affected areas, with poor visibilty resulting difficulty for motorists travelling into Edinburgh.
One driver in Fife reported visibility of around 80-120m.
An alert on Traffic Scotland’s website urged motorists crossing the bridges to “slow down” and “exercise caution”.
A spokesperson said: “Drivers are advised to slow down and exercise caution due to fog affecting driving conditions on the M90 Queensferry Crossing and surrounding areas.”
The fog comes as temperatures plummeted overnight, with large parts of Scotland waking up to a widespread frost.
After the fog clears, sunny spells will develop in the afternoon and it will feel milder with spells of rain pushing from the west in the evening.
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