Met Eireann is warning of rain and freezing cold temperatures but there's a brief respite on the way.
High pressure will bring long, dry spells with below-average rainfall expected towards the end of the week.
Today will see a cold and frosty start to the morning but any frost and ice will clear away to a bright day with long sunny spells.
But patchy cloud will develop in the northwest and it will turn cloudier in the south and southeast during the evening.
Temperatures will range between 7 and 9 degrees.
Tonight will be cold as the mercury is set to plummet to as low as -1 degrees with frost in some areas but it will be less cold in the south and southeast with temperatures of 3 to 5 degrees.
Temperatures are expected to rise overnight in a light to moderate easterly breeze.
Tomorrow will be dull and damp with scattered rain and drizzle spreading across the country from the south and east in the morning and afternoon.
More persistent rain will move into Connacht and Munster during the evening. Highest temperatures of 8 to 11 degrees expected.
Tomorrow night will see rain spread northeastwards across the country.
Clear spells and scattered showers will follow into Connacht and Munster as the rain clears overnight.
Temperatures will stay between 2 and 6 degrees.
Here is the forecast for the rest of the week:
Thursday
"Rain will gradually clear from the east and north through the morning and early afternoon to leave a mix of sunny spells and scattered showers, most frequent over the western half of the country with a slight chance of some hail later in the day.
"Highest temperatures of 7 to 10 degrees in light to moderate westerly winds.
Thursday night
"A generally dry night with clear spells and showers becoming more isolated. Lowest temperatures of 0 to +4 degrees in a light to moderate northwest breeze.
Friday
"Friday will be a bright day with sunny spells and well scattered light showers. Highest temperatures of 7 to 9 degrees in a light to moderate northerly breeze.
Friday night
"Another dry night with long clear spells, though there may be isolated drizzle patches near eastern and southern coasts. Lowest temperatures of 0 to +4 degrees in a light breeze.
Saturday
"Some patchy drizzle will spread across the country from the east on Saturday but there will be a good deal of dry weather overall with sunny spells. A cool day with highest temperatures of 6 to 8 degrees in moderate northeasterly winds."
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