Met Éireann is warning of sub-zero temperatures and wintry showers this week.
Unsettled weather is forecast over the coming days with sleet and snow on higher ground on Wednesday and Thursday.
Nighttime temperatures will fall to as low as -2C.
Top temperatures today will be between 6C and 9C, with a strong to gusty wind adding to the chill factor.
There will be showers tomorrow, especially across the north and west, with temperature highs of 10C.
While there are some dry and sunny spells expected by the end of the week, it will be cold, with widespread frost expected on Thursday night. Temperatures may dip to -1C that night, and to -"C on Friday night.
Sunday looks like being the best day of the week, with dry and bright weather expected.