The ESB's urging people to charge mobile phones and check torch batteries in case of power cuts this evening.
Lightning strikes knocked out supply to thousands of homes last night, and more storms are forecast today.
Status Yellow Thunder alerts have been issued by Met Éireann for Connacht and western Counties until 11pm tonight apart from some parts of Leinster.
There are also over 2,000 homes without power in Westport due to a fault in Carrowbeg.
Forecaster Matthew Martin says it's an evolving situation: