Gardai are advising people to continue to exercise extreme caution on the roads, with black ice now a major problem.
Motorists are asked not to make unnecessary journeys, and gardai say people should use public transport where possible.
Gardai are urging drivers to be conscious of the safety of pedestrians, and they're urging pedestrians to avoid walking on the road and wear hi-vis jackets.
Current indications are that temperatures are to remain very low and drop further later on and this will create further difficult driving conditions.
Numerous collisions and incidents were reported in Donegal this morning, as widespread black ice
led to the most dangerous driving conditions yet in the county. Three gritters went off the road in West Donegal, an indication of the seriousness of the situation.
The council says it began gritting at 6am, but it rained and froze over, and the county's roads were like ice rinks.
The council will delay gritting until 8am tomorrow (Sun), but says motorists cannot take it as read that treated roads will be safe.
Senior Council Roads Engineer Michael Mc Garvey says salt and grit supplies are being managed, but they have to be mixed, and that is compromising their effectiveness in places. He says the changed conditions are very serious......