Black ice has made many routes across northern England treacherous, say police.
Rain falling overnight has frozen on roads and pavements, with areas of Northumberland particularly affected.
Police have urged motorists to drive carefully, allow more time for their journeys and keep extra distance from the vehicle in front.
Temperatures are expected to fall well below zero overnight and remain low throughout Monday.
Freezing fog is also expected to linger in the North at the start of the week.