Those in the affected areas can expect a combination of rain, sleet and snow, with snow possibly reaching up to 4cm in Wales and across England and Scotland. Maximum temperatures ranging from 3 to 6C but 7 to 8C for central and southern Ireland.
Some of these showers will spread into central and eastern areas at times, with the odd flurry further south. Cold, with highest temperatures ranging 4 degrees Celsius in the north to 8 degrees Celsius in the south.
"Accumulations generally 1-2cm expected".
The outlook for the rest of the week is varied with wintry showers set to continue on Wednesday but relatively warmer weather and patchy rain predicted to see out the week.
It will be dry with sunny spells over the east.
As the rain moves south across the United Kingdom, temperatures will fall close to 0C causing ice to form.
According to Met Eireann, temperatures will plummet below freezing through much of this week with frost, icy patches and some wintry precipitation at times.
Today will see cloud thicken as the day progresses, bringing rain or sleet by this afternoon.
"It will be quite a sunny start to Monday once frost clears and will stay quite bright for most of the morning". Cold with frost and ice for sheltered areas. Cold, with lows of -2 to +2 degrees Celsius, in light westerly breezes. Friday looks set to be fairly decent with only clouds and spells of patchy rain set to arrive.
Dry otherwise with limited brightness - lengthiest in the far southeast with gentle southwesterly winds.