People are being warned to check conditions before swimming this weekend.
The RNLI along with the Coast Guard and Water Safety Ireland say cold water can lead to shock as temperatures drop and the evenings get darker.
They're advising swimmers of rip currents and unknown depths due to recent localised flooding.
People are being asked to check weather forecasts and tide information and to bring warm clothes and a hot drink after their swim.
Lead Water Safety Officer with the RNLI Linda Gene Byrne has this advice: