Thunderstorm and high temperature warnings have expired after another hot day in many parts of the country.
Met Éireann said the highest temperature recorded today - 30.1C - was reached at Shannon Airport in Co Clare.
The forecaster said that it will be another mild night with temperatures will not fall below 16C in places.
It will mostly dry, although showers are possible in the east and northeast.
Mist, drizzle and fog will develop across the southern half of the country by morning.
The temperature record for the month of May was broken at Shannon Airport yesterday, where the mercury hit 30.6C.
It followed another record earlier at Oak Park weather station, just outside Carlow town, with 29.7C recorded.
A temperature of 28.6C was reached at Shannon on Monday, breaking the previous May record of 28.4C, which was set at Ardfert in Co Kerry on 31 May 1997.
Tomorrow will be very warm in the east and north, according to Met Éireann, with highest temperatures of around 24C.
It will be cooler and duller elsewhere, with patchy drizzle and mist.
Meteorologist with Met Éireann, Linda Hughes, said that the hot weather is drawing to a close.
Speaking on RTÉ's Drivetime, she added that the temperatures were very unusual for May.
Ms Hughes said that the highest temperatures will be in the northeast tomorrow.
Forest fires are a possibility with the Department of Agriculture issuing an orange level advisory.
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A so-called "heat dome" of warm air from northern Africa trapped under a high-pressure system over western Europe is behind the high temperatures not usually seen until high summer.
The RNLI has said that despite the hot weather, the water temperature is still "very, very cold" and warned people to be aware of cold-water shock when swimming.
RNLI Water Safety lead Linda-Gene Byrne said cold-water shock occurs when the water temperature is below 15 degrees Celsius.
How to stay safe in the summer heat
Speaking on RTÉ's Morning Ireland, she said that people should try to acclimatise slowly instead of jumping straight in.
"If you hit the water ... if you jump straight into the water or if you accidentally fall in the water, you have a good chance of this affecting you.
"What happens is you get that involuntary gasping kind of a panic and a loss of breathing control as your body gets a sudden shock of that cold water hitting it."
She explained that "what you need to do if you get this cold water shock is remain calm. You go onto your back in the water, you stay calm and fight any instinct you have to panic or thrash around."
Ms Byrne also said that if anyone spots someone in trouble in the water they should call the emergency services first, then try to shout out to the person to float on their back.
She added that if there is anything like a buoyancy aid, or long pole that might reach the person, that should be used, while staying safe on the beach or riverbank.
