SMHI has issued yellow warnings for sudden ice slippage on Christmas Eve for parts of Götaland, Svealand and southern Norrland.
The risk is high that the treacherous black slip will strike in the middle of the Christmas traffic.
- It is sometimes called black slip.
It's not a meteorological expression, but it means that the roads look dry, it's very treacherous, says Lars Knutsson, meteorologist at SMHI to TT.
The rain moves in from the west during the evening.
The temperature at the road surface rises more slowly than in the air and can then be below zero when the rain hits it.
Then the rain freezes and it becomes slippery quickly.
Yellow warnings also on Boxing Day
And the roads don't look much better on Boxing Day.
Sudden ice slippage is then expected along the Norrland coast and the southern Västerbotten coast.
A yellow warning has also been issued for northern Dalarna and northernmost Värmland - there is expected to be heavy snowfall and between 10 and 15 centimeters of snow.