Met Eireann have issued an urgent Status Yellow rain and thunderstorm warning for all of Ireland as miserable conditions are expected.
The alert is in place from 9am on Wednesday until noon on Thursday for all 26 counties.
It reads: "Scattered heavy downpours and thunderstorms are expected in some areas today (Wednesday), tonight and for a time on Thursday. Localised flooding may occur where the rainfall is heaviest."
Meanwhile Thursday also looks set to bring drier conditions in some areas with some "hazy sunshine" even possible at times.
A Met Eireann forecaster said: "There'll be fairly widespread showers on Thursday, merging to give longer spells of rain at times. Further heavy downpours along with isolated thunderstorms will bring a risk of spot flooding.
"Dry periods between the showers with some hazy sunshine in places. Highest temperatures of 18 to 22 degrees with mostly light breezes but a fresh northerly breeze will develop along Atlantic coasts later.
"Scattered showers will continue into the night-time hours with some mist and fog setting in later. Another very mild and humid night with lowest temperatures of 13 to 16 degrees Celsius. Winds will be light and variable, though moderate to fresh northwesterly along Atlantic coasts."
And the rest of the week looks set to provide a mix of both sunshine and showers, but there are indications next week will bring more "calm" and "settled" conditions.
A forecaster added: "Friday will be a day of sunny spells and scattered showers, some heavy across eastern counties later. Highest temperatures of 16 to 21 or 22 degrees Celsius, warmest in the east, with light northwest winds. Showers will become fewer overnight with long clear spells developing.
"A little cooler that previous nights with overnight lows of 9 to 14 degrees Celsius, in light to moderate west to northwest breezes.
"Feeling fresher on Saturday with a mix of sunny spells and just well scattered showers. Highest temperatures of 15 to 18 degrees Celsius, in a light northwest breeze.
"Beginning cloudy on Sunday with scattered outbreaks of rain. Sunny spells will develop into the afternoon with just well scattered showers and mostly sunny conditions to end the day. Feeling autumnal, in light northerly breezes, with highest temperatures of 14 to 17 degrees Celsius.
"Current indications suggest the early days of next week will bring a lot of calm settled weather, though mist and fog may linger locally."
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