The country is officially feeling the bite.
Wintry showers with strong winds, biting cold temperatures, snow, sleet and hail are extending to all areas this afternoon.
Met Eireann have confirmed wintry showers to be "increasingly falling as snow to lower levels as the day goes on".
And the temperatures have now dropped to between 3 and 5 degrees Celsius.
Dozens of gritting lorries were being prepared across the country last night as the first extensive snowfall of the winter is set to begin over Ulster and Connacht.
A 'status orange' weather alert went into effect at 6pm yesterday and will remain until 6pm tomorrow for areas in the north and north-west.
Met Éireann is warning residents living in counties Cavan, Monaghan, Donegal, Leitrim, Mayo and Sligo to brace themselves for extreme weather that could have a "significant impact".
It's a wet morning in many areas but so far no snow or ice reported. There is sleet in Manorhamilton though. https://t.co/xIOpAblVS1— AA Roadwatch (@aaroadwatch) January 12, 2017
KILKENNY: Collision on the M9 Dublin/ Waterford Rd southbound between J11 Mullinavat and J12 Grannagh on the N9. https://t.co/qvBPcgxUj8— AA Roadwatch (@aaroadwatch) 12 January 2017
DUBLIN Heavy on M50 northbound from J12 Firhouseto J11 Tallaghtwhere a collision has cleared after the off-ramp https://t.co/r19oH1u8F2— AA Roadwatch(@aaroadwatch) 12 January 2017
AA Roadwatch is urging motorists to slow down this morning and to stay a safe distance from the vehicle in front.
Bitterly cold winds moved in from the Atlantic yesterday as a precursor to the extremely cold and wintry weather that was expected to bring showers of sleet, snow and hail from last night.
Dublin Traffic: Collision on M50 Jct 11 Tallaght Northbound,— An Garda Síochána (@GardaTraffic) January 12, 2017
DUBLIN: Emergency services have left the jct of Navan Rd and Auburn Ave after a crash. https://t.co/xIOpAblVS1— AA Roadwatch (@aaroadwatch) January 12, 2017
Temperatures were due to plunge to between -1C and -2C overnight, and will struggle to rise to between just 2C and 4C during the daytime today and tomorrow.
Moderate accumulations of snow were expected to fall by this morning on lower-lying areas.
But those living in mountainous areas or on higher ground can expect to wake up to significant snowfall.
Coupled with strong, bitterly cold winds, they also face a risk of drifting and blowing snow and blizzard-like conditions that could severely reduce visibility on the roads.
Added to the mix is also the risk of scattered thunderstorms.
Met Éireann also issued a less severe 'status yellow' snow and ice alert for Munster and Leinster, as well as in Co Galway and Co Roscommon.
This yellow alert went into effect at 5am and is expected to remain until 6pm tomorrow. Residents in affected areas should be aware of the challenging weather and take precautions. Some accumulation of snow is expected on lower ground, with more widespread accumulations on higher ground.
Areas along the east coast of Leinster, including Dublin and south Leinster, were likely to see more scattered showers.
But very icy conditions are forecast for most areas.
Local authorities, in conjunction with Transport Infrastructure Ireland, were on standby last night with stores of salt and gritting equipment ready to be deployed on major and secondary roads and footpaths.
They attended a meeting of the National Emergency Co-ordination Group for Severe Weather yesterday.
It aims to ensure that all of the relevant authorities - including An Garda Síochána, the HSE, Defence Forces and all State transport operators - are monitoring the impact of the severe weather in their respective areas and are able to put into place their severe weather plans as needed.
In Donegal, where the worst of the snow is expected, the county council last night deployed 23 gritting lorries, which have all been adapted to also operate as snow ploughs.
"Staff will work across all main routes right throughout this weather alert and we are urging motorists to take extra care over the next couple of days," said a Donegal County Council spokeswoman.
Meanwhile, the public is being urged to keep abreast of local weather forecasts and conditions when planning journeys or other activities and to heed safety messages issued by relevant agencies.
"We haven't had truly icy conditions yet this winter but they may be on the way," Conor Faughnan, AA director of consumer affairs said. "Icy conditions and snow are a real danger for motorists."
The public is also being asked to call on elderly relatives and neighbours to offer assistance.
Find information on public safety at www.winterready.ie.