MET Eireann has warned that fierce winds will lash the west and north coasts after issuing an orange weather alert.
Forecasters are predicting winds of up to 130kph, and the coast guard is advising people to exercise extreme caution.
The worst weather is expected in Galway, Mayo, Donegal, Sligo, Clare, Kerry and Limerick.
Dublin will see rain or hail and thunderstorms throughout today.
The coast guard at Malin Head was reporting gale-force winds last night.
Met Eireann said the unsettled weather will continue for the rest of the week and into next weekend.
More than 800 homes in the west were left without electricity yesterday.
ESB crews worked throughout the day to restore power, with Galway and Mayo badly hit.
The worst-affected areas were in Renvyle and Clifden in Co Galway, where 350 homes were left without power. Homes in Carna, Recess, Kilcolgan, Woodford, Peterswell and Kiltartan were also in darkness.
Several of the power outages were caused by lighting strikes.
People have been warned not to go out on exposed cliffs or in coastal areas and not to take part in water sports.