Motorists have been advised to take extra care this morning as frost and ice are causing problems on a number of roads across the country.
Most road temperatures are below zero, as low as -6 degrees on the N3 at Kells, -5.9 degrees on the N6 at Kilbeggan and -5.8 degrees on the N2 at Monaghan.
AA Roadwatch advises drivers to use fog lights in affected areas but to remember to switch them off afterwards.
Connacht is particularly affected by the cold weather with icy conditions on all routes across Roscommon, Mayo, and Donegal.
Leinster is also badly affected with difficult driving conditions reported in counties Kildare, Laois, Westmeath and Kilkenny.
Temperatures are not expected to rise beyond 2 or 3 degrees today.
Age Action has urged people to call in on older neighbours and family members to ensure they have enough daily essentials and adequate heating.
While the cold weather may have returned with a vengeance it was a different story last month with above-average temperatures the norm, according to new data released by Met Éireann.
Weather stations in the west and midlands reported the warmest January since 2007, while stations in the southwest measured the warmest January temperatures in the last ten years.
Both minimum and maximum daily temperatures were above normal, with stations in the west and southwest recording the highest minimum temperatures in the last ten to 19 years. The highest maximum temperature was 13.1 degrees, recorded at Shannon airport on January 3rd.
Rainfall was recorded as above average at almost all stations, while sunshine stations reported the dullest January in five to 19 years. January also experienced little in the way of frost, but wind speeds were above average, gusting gale-strength at times on most days.