Thick fog covered almost all of the Netherlands on Tuesday morning, cutting visibility to less than 20 metres in some places and causing long tailbacks and a head-on crash in Friesland. The national weather service KNMI issued a code yellow warning for the whole country except Zeeland, the Wadden Islands, the IJsselmeer and Wadden Sea areas and parts of Limburg. The warning runs from 11.30pm on Monday until midday on Tuesday.