Drivers across large parts of western Sweden in particular face a high risk of black ice over the coming days.
Black ice – often called svarthalka or blixthalka in Swedish – is notoriously treacherous because it is virtually invisible, while leaving road surfaces dangerously slick.
It typically forms when wet roads freeze as temperatures hover around 0C.
The warning, issued by the Swedish Transport Administration, covers significant areas of central and western Sweden, though other regions may also be affected.
"The Swedish Transport Administration works preventively with anti-icing measures," said Jonas Nilsson, the agency's road maintenance manager in western Sweden.
"But black ice can form suddenly in patches, making it difficult to predict. In certain parts of western Sweden, temperatures remain above freezing around the clock, but the road surface can be colder than the air, and temperatures can shift rapidly during the autumn," he said in a statement.
To reduce the risk of accidents, the agency urges motorists to accelerate and brake gently, and to ensure they have switched to winter tyres.
Swedish law states that all cars must be equipped with winter tyres between December 1st and March 31st if the weather conditions require it – but remember that even if it isn't yet December, you are always responsible for ensuring that your vehicle is safe.
Studded tyres – a type of winter tyre with added studs for additional traction – are allowed between October 1st and April 15th, or in wintery driving conditions.