The risk of black ice is greatest when the weather clears up after rain or fog and the temperature is around 0 °C.
Places and conditions where the risk of black ice is increased:
- Roads along open water – Wind and moisture quickly make the road surface slippery.
- Roads through open farming landscapes – Wind that blows over the fields can carry snow that polishes the road surface.
- Bridges and viaducts – Roads are quickly chilled from both below and above. If they are near open water, moisture make them even more slippery.
- Freezing rain – Rain that looks like normal rain but freezes immediately upon contact with the road.
- Shady forest areas – The moisture remains on the road surface and turns into ice if it is cold enough.
- Moist roads and clearing weather – Risk of the road surface freezing when the temperature drops.