DONEGAL County Council says it is already responding to an Orange Weather Alert for snow and ice which has been issued by Met Eireann.
Gritting lorries began treating main roads across Donegal at 5pm, says the council.
The lorries – some fitted with snow ploughs – will be deployed again into the early hours of Tuesday with 6cm of snow likely in some areas.
Gardai say roads in higher areas are already treacherous tonight, with officers urging caution on the Barnesmore Gap and the back of Errigal road between Dunlewey and Termon.
Met Eireann’s Orange Alert for snow and ice is from 9pm this evening until 6pm on Tuesday.
This means there is a high possibility of disruption which could close schools and businesses.