Ireland is set for a dull and wet start to the day before things begin to pick up in the evening, with showers clearing to the southeast.
Met Eireann has predicted temperatures to fall below zero before a mini-heatwave hits Ireland just in time for St Patrick's Day.
Connacht and west Ulster will see the worst of the conditions today, with rain expected to remain until later this afternoon.
READ MORE: Will it snow in Ireland? Met Eireann latest forecast as -3C cold snap hits before big change
A forecaster said: "Rain the West tomorrow will slowly move East and some showers Wednesday and a few on Thursday but dry and settled for Friday and weekend with plenty of sunshine too!"
Here is a more detailed look at this week's forecast.
Today, March 15
Mostly cloudy this morning with just a few clear spells. Rain in Connacht and west Ulster early this morning will slowly move southeastwards through the rest of the day, but much of Leinster will stay dry until the evening.
Highest temperatures of 7 to 11 degrees with a moderate to fresh southerly breeze.
Tonight will start mainly cloudy with scattered outbreaks of rain, but drier and clearer conditions will gradually extend across the country from the west overnight.
Most areas will be dry by morning, although the rain may linger in southeast Leinster.
It will become very cold and frosty in most places, with temperatures dropping to between -3 and 0 degrees; however, it will be less cold in the southeast, with temperatures not falling below 3 to 5 degrees.
Winds will be light and variable, so mist and fog patches will form.
Wednesday, March 16
Wednesday morning will be cold, bright and frosty, and any rain in the southeast will clear.
There will be spells of sunshine throughout the day, with well-scattered showers, mainly affecting the west and northwest.
Highest temperatures of 8 to 11 degrees in a light to moderate west to southwest or variable breeze.
Any showers will clear early on Wednesday night, leaving dry and clear conditions for a time.
However, cloud will move in from the Atlantic overnight, and showery rain will develop across the country's western half.
Lowest temperatures of 0 to 4 degrees with a light to moderate southerly wind, freshening along west and northwest coasts later.
St Patrick's Day
The morning will be mostly cloudy with showery rain moving eastwards across the country, but it will become drier and brighter through the afternoon, with showers becoming isolated.
At times, it will be breezy with a moderate to fresh southwest to west wind, but this will ease by evening.
Highest temperatures of 8 to 13 degrees, mildest in the south and east.
Thursday night will be dry, and skies will become clearer overnight.
Winds will be light and variable, becoming southeasterly later.
Lowest temperatures of -2 to +3 degrees, with frost in parts of the northeast and east.
Friday, March 18
Friday will be dry with long sunny spells and mild, too, with temperatures reaching 10 to 15 degrees.
There will be a light to moderate south to southeast breeze.
Friday night will be dry and clear with a light to moderate southeasterly breeze.
Lowest temperatures of 4 to 8 degrees.
Saturday, March 19
Saturday looks set to be dry and mild with sunny spells.
Highest temperatures of 10 to 15 degrees in a light to moderate southeasterly breeze.
A dry and clear night with light east to southeast winds.
Lowest temperatures of 1 to 6 degrees, coldest in the north.
