The very cold weather will continue until Sunday, with scattered snow showers, freezing temperatures and dangerous road conditions, according to a severe weather warning issued by Met Éireann yesterday.
Air temperatures will drop to between zero and minus 5 degrees Celsius, while ground temperatures are expected to fall to between minus 5 to minus 10 degrees over the coming nights.
This week's weather conditions are a result of bitter winds travelling directly from the North Pole and bringing with them showers of hail, sleet and snow, according to Evelyn Cusack of Met Éireann.
This cold snap will produce further wintry showers and between 3-5cm of accumulated snow in places, particularly in the north and northwest.
During Sunday evening and into Sunday night, possibly a heavy snowfall may be accompanied by strong winds, giving the potential for blizzard conditions.
The sub-zero temperatures resulted in treacherous road conditions and led to the closure of schools across Sligo, Donegal, Mayo and most of north Leitrim yesterday as Bus Éireann and private operators cancelled school runs throughout the region.
The National Safety Council has advised all road users to take extra care when driving.
Spokesman Brian Farrell cautioned motorists to "expect the unexpected" and to rigorously check local and national forecasts before starting out.
Extra time should be allowed for all journeys and motorists should remain vigilant for potential black ice, frost and skid traps on roads. Main routes in Northern Ireland were passable, with motorists urged to negotiate the traditionally treacherous Glenshane Pass in Co Derry with care.