Status yellow weather warnings have been issued for eight counties on Saturday evening, with heavy and thundery rain forecast.
Met Éireann issued two separate yellow warnings. The first affects Carlow, Dublin, Kildare, Kilkenny, Wicklow and Wexford, which will come into effect at 5pm on Saturday until 4am on Sunday.
The second is for Louth and Meath, which comes into effect on 8pm on Saturday until 6am on Sunday.
The warnings state a spell of “heavy or thundery rain combined with saturated ground conditions” could result in flooding, difficult travel conditions and disruption to outdoor events.
The UK Met Office also issued a yellow weather warning for five counties in Northern Ireland. The warning, covering Antrim, Armagh, Down, Fermanagh and Tyrone, will come into effect at 9pm on Saturday until midday on Sunday.
The warnings are in place as thousands of people prepare to take to the streets of the capital for the annual Dublin marathon on Sunday.
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Overall, Met Éireann said early mist and fog patches will clear on Saturday morning to give sunny spells and scattered showers, some of which will be heavy and prolonged with a chance of spot flooding.
Rain will develop in the southeast later in the afternoon. afternoon and will move north and westwards through the evening, heavy and perhaps thundery at times with local flooding possible.
Highest temperatures of 10 to 13 degrees are forecast, and tides will be very high along all coasts so coastal flooding is possible.
Saturday night will be a wet night for most people, with some heavy and possibly thundery downpours and the ongoing chance of localised or coastal flooding.
The southwest may escape the worst of the rain, and it will turn drier generally in southern parts later in the night, with mist and fog developing, the forecaster said. However further heavy showers may arrive in the southeast towards morning.
On Sunday, there will be further showers or longer spells of rain, with some heavy downpours and the chance of localised flooding.
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Sunday night will be similar, with fog developing in many areas. Localised heavy or thundery showers are still possible in places.
Bank holiday Monday will continue to be largely unsettled, with some heavy showers and thunderstorms and spot flooding possible.
Further heavy showers are expected overnight with temperatures falling to between 3 and 6 degrees. The showers will become confined to the northeast coast by morning.
