Met Eireann have issued two urgent Status Yellow weather warnings for seven counties as miserable conditions are set to hit.
The first alert is in place for Donegal, Galway, Leitrim, Mayo and Sligo from midnight on Thursday until 3am on Saturday as heavy rain and flooding are possible.
It reads: "Prolonged rain with heavier bursts at times, heaviest and most persistent later on Friday. Significant accumulations are possible in upland areas. Risk of localised flooding."
While the second warning is in force for Cork and Kerry from noon on Thursday until 3am on Saturday.
It reads: "Prolonged rain with heavier bursts at times, heaviest and most persistent later on Friday. Significant accumulations are possible in upland areas. Risk of localised flooding."
It comes as the country will see a stark split in conditions on Thursday with the east and midlands enjoying some dry and bright weather for most of the day.
There will be little respite in the west however as a further "pulse" of heavy rain is set to move in from the south in the latter part of Friday.
A Met Eireann forecaster said: "Dull, humid and breezy on Thursday with outbreaks of rain continuing in western counties, heavy and persistent at times, especially on high ground with a risk of localized flooding. In contrast somewhat brighter and a lot of dry weather for the midlands and east, with just a little patchy light rain or drizzle at times. Unseasonably warm with highest temperatures of 16 to 20 degrees, in moderate to fresh southerly winds.
"Patchy rain and drizzle in all areas on Thursday night, again heaviest over high ground in the south and west. Very mild again with temperatures not falling below 14 to 16 degrees, in a light to moderate southerly breeze.
"Mostly cloudy with a mix of patchy rain and drizzle with some drier weather early on Friday, before another pulse of heavier rain pushes up from the south through the afternoon and evening. The heaviest of the rain will be over high ground in the southwest and west with a continued risk of local flooding. Warm with highs of 15 to 19 degrees, in a light to moderate southerly breeze.
"The heaviest of the rain will move into eastern parts on Friday night."
However there is some better news this weekend as the horrendous conditions are set to be replaced by a spell of high pressure moving in on Saturday.
A forecaster added: "Cloudy and wet in the east to start on Saturday, but a clearance to sunny spells and showers will develop in the west by morning and move eastwards through the day. Highs again of 15 to 19 degrees, in light westerly winds.
"Mostly dry with good sunny spells and just a few showers in the north. A cooler day with temperatures returning to near average, with highs of 13 to 15 degrees, in a light westerly breeze.
"Mostly dry next week with a mix of sunny spells a few showers. Daytime temperatures around the seasonal norm of 12 to 15 degrees, with some chilly nights and generally light winds."
